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Chapter 10 Single-Variable, Independent-Groups Designs 10.1 Variance 1) Experimental design A) refers to trying things out at random. B) is the random assignment of conditions. C) involves the measurement and control of variance. D) focuses on the measurement of contingencies. Answer: C Rationale: Experimental design involves planning and structuring experiments to ensure the measurement and control of variance. This control is essential for isolating the effects of the independent variable and drawing valid conclusions from the study. 2) In experimentation, designing the procedures A) must be done before making observations. B) is flexible and the procedures can be altered at any time. C) is carried out immediately following observation. D) includes analyzing the obtained data. Answer: A Rationale: Designing procedures in experimentation must be done before making observations to ensure that the study is conducted in a systematic and controlled manner. This helps to minimize bias and maximize the validity of results. 3) A clear experimental design should be developed A) before making any observations. B) after observations have been made. C) at the data collection phase. D) before beginning to review literature in the area. Answer: A Rationale: Developing a clear experimental design should precede making any observations to ensure that the study is properly planned and executed. This helps to minimize errors and biases in data collection and analysis. 4) The statement "variation is necessary to carry out experiments" A) is true only in experiments involving human participants. B) is not true in nearly 30% of all experimentation. C) refers only to the importance of having very different participants in each group. D) is always true in experiments of any kind. Answer: D Rationale: Variation is necessary in experiments of any kind to observe differences between groups or conditions. This allows researchers to test hypotheses and draw meaningful conclusions about the effects of the independent variable. 5) In order to study causal relationships, A) the null hypothesis must not be rejected. B) external validity is essential. C) we must use a t-test or F-test. D) there must be variation of the independent variable. Answer: D Rationale: Variation of the independent variable is necessary to study causal relationships because it allows researchers to observe how changes in the independent variable lead to changes in the dependent variable. This enables researchers to establish causality. 6) One basic purpose of experimental design is A) to reduce the number of participants needed. B) to control variance. C) to keep the alpha level below .05. D) to observe contingencies. Answer: B Rationale: One basic purpose of experimental design is to control variance, ensuring that extraneous factors do not confound the results. This helps researchers attribute any observed effects to the manipulated variables. 7) Without ________, there would be no differences between groups to test. A) nonmanipulated independent variables B) degrees of freedom C) uniformity D) variation Answer: D Rationale: Variation is necessary in experimental designs to create differences between groups or conditions. Without variation, there would be no basis for testing hypotheses or drawing conclusions about the effects of the independent variable. 8) In order for us to study causal relationships among variables, it is necessary for A) the independent variable to demonstrate variation. B) the dependent variable to be a constant. C) the independent variable to demonstrate that it is randomly distributed. D) there to be extraneous variation. Answer: A Rationale: To study causal relationships, the independent variable must demonstrate variation so that researchers can observe how changes in the independent variable relate to changes in the dependent variable. This variation allows researchers to establish causality. 9) In experiments, we hope to find A) between-groups variance. B) a reduction in sampling error. C) within-groups variance. D) an increase in sampling error. Answer: A Rationale: In experiments, researchers hope to find between-groups variance, as this indicates differences between experimental conditions or groups that can be attributed to the manipulated variables. This variance allows researchers to test hypotheses and draw conclusions about the effects of the independent variable. 10) It is necessary to design and carry out experiments so that the experimental conditions A) are in harmony with each other. B) are clearly similar to one another. C) make sense to the participants. D) are clearly different from each other. Answer: D Rationale: Experimental conditions need to be clearly different from each other to allow for meaningful comparisons. This ensures that any observed differences between conditions can be attributed to the independent variable rather than extraneous factors. 11) An experimenter hopes to find that the predicted variation A) leads to accepting the null hypothesis. B) reduces the difference between-groups. C) increases the within-groups variation. D) is due to the experimental manipulation. Answer: D Rationale: The predicted variation, as mentioned in option D, is expected to be due to the experimental manipulation. This aligns with the purpose of conducting experiments, where researchers manipulate the independent variable to observe its effect on the dependent variable. 12) Extraneous variation generally A) reduces internal validity. B) enhances internal validity. C) has no effect on internal validity. D) affects internal validity only when there are more than two levels of the independent variable. Answer: A Rationale: Extraneous variation typically reduces internal validity by introducing confounding factors that can obscure the true relationship between the independent and dependent variables. Option A accurately reflects this notion. 13) Error variance is A) between-groups variance. B) within-groups variance. C) between-groups variance divided by within-groups variance. D) the major component causing differences between experimental conditions. Answer: B Rationale: Error variance represents the variability within groups, reflecting random fluctuations or measurement error that are not systematically related to the independent variable. Option B correctly identifies error variance as within-groups variance. 14) Nonsystematic within-groups variance is called A) the standard error. B) error variance. C) excess variance. D) expected variance. Answer: B Rationale: Nonsystematic within-groups variance, which represents random variability within groups, is termed error variance because it reflects the unexplained variance in the dependent variable not attributable to the independent variable. Option B accurately labels this concept. 15) Which of the following is most closely associated with the concept of "sampling error"? A) operational definitions in experimentation B) differences between males and females on the dependent measure C) electronic hardware failures during sampling D) natural variability among the means Answer: D Rationale: Sampling error refers to the natural variability among the means obtained from different samples drawn from the same population. Option D correctly identifies this association. 16) The hypothesis that the independent variable has influenced the dependent variable is the A) null hypothesis. B) alternative concepts hypothesis. C) research hypothesis. D) equivalent constraint hypothesis. Answer: C Rationale: The hypothesis that the independent variable has influenced the dependent variable is the research hypothesis, as stated in option C. It represents the expected relationship between the variables under investigation. 17) Controls are necessary to A) reduce extraneous variation. B) enhance extraneous, between-groups variation. C) neutralize all differences between groups. D) increase within-groups variation. Answer: A Rationale: Controls are implemented to reduce extraneous variation, as stated in option A, thereby increasing the internal validity of the experiment by minimizing the influence of confounding variables. 18) Extraneous variance in a study A) is unwanted. B) is highly desirable. C) is desirable in some circumstances. D) has no impact on the chances of getting statistical significance. Answer: A Rationale: Extraneous variance, representing variability in the dependent variable not attributable to the independent variable, is unwanted because it can obscure the true effects of the independent variable on the dependent variable. 19) Natural variation among samples drawn from the same population is A) measurement error. B) sampling error. C) variation error. D) natural error. Answer: B Rationale: Natural variation among samples drawn from the same population is referred to as sampling error, as described in option B. It reflects the variability in sample statistics that occurs due to random sampling. 20) Which of the following is NOT a source of between-groups variance? A) experimental effects B) confounding variables C) sampling error D) control effects Answer: D Rationale: Control effects typically contribute to between-groups variance by minimizing the influence of extraneous variables, so option D is incorrect. The other options represent sources of between-groups variance, as they involve factors that systematically differ between experimental conditions. 21) Two sources of systematic between-groups variation are A) experimental and extraneous variance. B) sampling deviation and experimental variance. C) sampling deviation and extraneous variance. D) control variance and standard variance. Answer: A Rationale: Experimental variance refers to the variability in scores that is systematically related to the manipulation of the independent variable. Extraneous variance, on the other hand, refers to variability in scores that is not systematically related to the independent variable but can still affect the dependent variable. Both of these sources contribute to systematic between-groups variation. 22) Between-groups variance is a function of A) experimental variance only. B) experimental effects and confounding variables. C) error variance only. D) general variance. Answer: B Rationale: Between-groups variance reflects differences in scores between different groups in an experiment. It is influenced by both the effects of the independent variable (experimental effects) as well as any confounding variables that may inadvertently influence the dependent variable, thereby affecting the group differences. 23) Between-groups variance is a function of A) both experimental effects and confounding variables. B) experimental effects. C) confounding variables. D) experimenter effects. Answer: A Rationale: Between-groups variance represents the variability in scores between different groups in an experiment. This variance is influenced by both the intended effects of the independent variable (experimental effects) and any unintended influences from confounding variables. 24) Error variance is another name for A) systematic between-groups variance. B) experimental variance. C) nonsystematic within-groups variance. D) extraneous variance. Answer: C Rationale: Error variance, also known as nonsystematic within-groups variance, refers to the variability in scores within each group that is not systematically related to the independent variable. It represents random fluctuations or measurement error that affect individual scores within each group. 25) The systematic effects of uncontrolled confounding variables is termed A) the effect size. B) extraneous variance. C) experimental variance. D) sampling error. Answer: B Rationale: Extraneous variance refers to the systematic effects of uncontrolled confounding variables in an experiment. These variables can introduce variability in scores that is not directly attributable to the independent variable, thereby influencing the results. 26) The two primary sources of systematic between-groups variance are A) experimental variance and error variance. B) extraneous variance and error variance. C) experimental variance and extraneous variance. D) error variance and individual differences. Answer: C Rationale: The two primary sources of systematic between-groups variance are experimental variance, which reflects the effects of the independent variable, and extraneous variance, which reflects the effects of uncontrolled confounding variables. 27) Statistical tests CANNOT tell us whether A) the combination of experimental and extraneous variance is large enough to differentiate the groups. B) there is a significant difference between groups. C) there is a reliable difference between groups. D) the observed difference is due to experimental or extraneous variables. Answer: D Rationale: Statistical tests can determine whether there is a significant difference between groups, but they cannot determine the specific source of that difference, whether it is due to the experimental manipulation or extraneous variables. Identifying the source of the observed difference requires careful experimental design and control. 28) It is important for an experiment to have A) high experimental variance. B) high extraneous variance. C) low experimental variance. D) high error variance. Answer: A Rationale: High experimental variance reflects substantial variability in scores that can be attributed to the manipulation of the independent variable. This variability allows for better discrimination between experimental conditions and enhances the likelihood of detecting significant effects. 29) The variation due to chance factors among individual participants within a group is termed A) error variance. B) individual differences. C) experimental variance. D) extraneous variance. Answer: A Rationale: Error variance refers to the variability in scores within each group that is not systematically related to the independent variable. It includes random fluctuations and measurement error that affect individual scores within each group. 30) It is impossible to directly measure A) extraneous variance. B) error variance. C) between-groups variance. D) within-groups variance. Answer: A Rationale: Extraneous variance represents the systematic effects of uncontrolled confounding variables, which by definition are not directly measured or controlled by the experimenter. While experimental designs aim to minimize extraneous variance, it cannot be directly measured because it encompasses unknown or unmeasured factors influencing the dependent variable. 31) Error variance A) is due to nonsystematic factors. B) is the major component of experimental variance. C) is due to systematic factors. D) is a minor concern in experimentation. Answer: A Rationale: Error variance arises from nonsystematic factors, such as random variability or uncontrolled influences, and it contributes to the variability observed within groups in an experiment. Options B, C, and D are incorrect because error variance is not the major component of experimental variance, it is not due to systematic factors, and it is not a minor concern in experimentation. 32) If error variance were to occur in an experiment, A) the mean of the groups would be increased. B) the mean of the groups would be decreased. C) participants would be affected systematically. D) participants would be affected at random. Answer: D Rationale: Error variance affects participants randomly, leading to variability in their responses or outcomes within groups. Options A, B, and C incorrectly suggest systematic effects, which are not characteristic of error variance. 33) Nonsystematic, within-groups variability A) has differential effects on only the experimental group. B) has random effects. C) has no effects on the outcome. D) cannot be controlled. Answer: B Rationale: Nonsystematic, within-groups variability refers to random effects that contribute to error variance. It affects the outcome by introducing variability but cannot be controlled easily. Options A, C, and D are incorrect because within-groups variability does not necessarily have differential effects only on the experimental group, it does affect the outcome, and it can be controlled to some extent. 34) Which of the following does NOT increase error variance? A) random factors B) individual differences C) experimenter error D) systematic effects of the independent variable Answer: D Rationale: Error variance is increased by random factors, individual differences, and experimenter error, all of which contribute to nonsystematic variability within groups. Systematic effects of the independent variable reduce error variance by accounting for some of the variability observed. Therefore, option D does not increase error variance. 35) Error variance is due to ________ factors that affect individuals within a group. A) systematic B) methodical C) random D) experimental Answer: C Rationale: Error variance is due to random factors that affect individuals within a group, contributing to the nonsystematic variability observed in their responses or outcomes. Options A, B, and D incorrectly suggest systematic or deliberate influences, which are not characteristic of error variance. 36) Nonsystematic, within-groups variability is also called A) error variance. B) standard variance. C) common deviation. D) combined range. Answer: A Rationale: Nonsystematic, within-groups variability is synonymous with error variance, which refers to the random variability observed within groups in an experiment. Options B, C, and D are incorrect because they do not accurately describe this type of variability. 37) The experimenter hopes to find A) high error variance. B) low experimental variance. C) high experimental variance. D) high within-groups variance. Answer: C Rationale: The experimenter hopes to find high experimental variance because it indicates that the independent variable has a substantial effect on the dependent variable, allowing for meaningful comparisons between groups or conditions. Options A, B, and D do not directly reflect the experimenter's goal. 38) Error variance refers to A) nonsystematic between-groups variance. B) systematic within-groups variance. C) nonsystematic within-group variance. D) systematic between-groups variance. Answer: C Rationale: Error variance refers to nonsystematic within-group variance, which arises from random or uncontrolled factors contributing to variability in participants' responses or outcomes. Options A, B, and D incorrectly describe other types of variance. 39) Which of the following is due to the effects of the independent variable? A) between-groups variance divided by within-groups variance B) within-groups variance C) experimental variance D) internal validity Answer: C Rationale: Experimental variance reflects the variability in the dependent variable that can be attributed to the effects of the independent variable, providing evidence of the relationship between them. Options A, B, and D do not specifically pertain to the effects of the independent variable. 40) An experiment is designed to A) maximize within-groups variance. B) maximize error variance. C) minimize experimental variance. D) maximize experimental variance. Answer: D Rationale: In experimental design, researchers often aim to maximize experimental variance to increase the sensitivity of their study to detect significant effects of the independent variable on the dependent variable. Options A, B, and C do not align with this typical goal of experimental design. 41) Experimental variance A) should be avoided whenever possible in an experiment. B) is due to the effects of the independent variable. C) often creates confounding factors in a study. D) tends to reduce sample size. Answer: B Rationale: Experimental variance refers to the variability in the dependent variable that is attributable to the effects of the independent variable. Therefore, option B correctly identifies experimental variance as arising from the independent variable. 42) Sources of error variance include A) individual differences and measurement error. B) ex post facto error and measurement error. C) individual differences and ex post facto error. D) ex post error and matching differences. Answer: A Rationale: Error variance arises from factors other than the independent variable that contribute to variability in the dependent variable. Individual differences and measurement error are examples of such factors, as stated in option A. 43) Nonsystematic within-group random errors A) affect the mean score of the group but not the variance. B) tend to cancel each other out. C) do not cancel each other out within the group. D) influence participants in a group in one direction. Answer: B Rationale: Nonsystematic within-group random errors tend to balance out across participants within a group, leading to cancellation of their effects, as described in option B. 44) If we do not observe a sufficiently large between-groups variance, then we have not observed A) experimenter effects. B) an effect of the dependent variable. C) enough samples. D) an effect of the independent variable. Answer: D Rationale: In experimental designs, the between-groups variance reflects the variance in the dependent variable that is attributable to the independent variable. Therefore, if there is not a significant between-groups variance, it suggests that the independent variable did not have a noticeable effect, as indicated in option D. 45) Two forms of variance are A) systematic between-groups variance and nonsystematic within-groups variance. B) systematic within-groups variance and standard variance. C) nonsystematic between-groups variance and systematic within-groups variance. D) nonstandard within-groups variance and standard between-groups variance. Answer: A Rationale: Systematic between-groups variance refers to the variability in the dependent variable that can be attributed to the independent variable, while nonsystematic within-groups variance refers to the remaining variability within groups that cannot be attributed to the independent variable, as stated in option A. 46) In order to support the hypothesis that the independent variable has influenced the dependent variable, A) a significantly high within-groups variation is necessary. B) careful reduction of all variation is necessary. C) a significantly high between-groups variation is necessary. D) a sample size of at least 30 is necessary. Answer: C Rationale: A significantly high between-groups variation indicates that the differences between groups are likely due to the manipulation of the independent variable, supporting the hypothesis that the independent variable influenced the dependent variable, as indicated in option C. 47) The two major types of variance in research are systematic between-groups variance and A) nonsystematic within-groups variance. B) nonsystematic between-groups variance. C) systematic within-groups variance. D) systematic between- and within-groups variance. Answer: A Rationale: The major types of variance in research are systematic between-groups variance, which is attributable to the independent variable, and nonsystematic within-groups variance, which is the residual variance within groups, as described in option A. 48) The ANOVA procedure depends on calculations of A) the size of the difference between the means of the two groups. B) both the variability within-groups and the variability between-groups. C) levels of the independent variable. D) preliminary t-tests. Answer: B Rationale: The ANOVA procedure compares the variability between groups to the variability within groups to determine if the differences between group means are statistically significant. Therefore, it depends on calculations of both within-groups and between-groups variability, as stated in option B. 49) The greater the extraneous and/or error variance, A) the more difficult it becomes to show the effects of experimental variance. B) the easier it becomes to show the effects of experimental variance. C) the more difficult it becomes to perform the F-test. D) the easier it becomes to show a causal effect of the independent variable on the dependent variable. Answer: A Rationale: Extraneous and error variance can obscure or dilute the effects of the independent variable, making it more challenging to detect significant effects of the independent variable on the dependent variable, as indicated in option A. 50) In the F-ratio, the within-groups variance A) is the numerator. B) is the denominator. C) is always greater than between-groups variance. D) has a minor effect on the means of the groups when the experimental manipulation also has a strong effect. Answer: B Rationale: In the F-ratio, the within-groups variance is the denominator, representing the variability within groups. This variance is compared to the between-groups variance (numerator) to determine the ratio of systematic variance to nonsystematic variance, as described in option B. 51) The denominator of the F-test reflects A) experimental, extraneous, and error variance. B) experimental variance. C) error variance. D) between-groups variance. Answer: C Rationale: The denominator of the F-test represents the within-groups variance or error variance. It reflects the variability of scores within each group or condition, which serves as the baseline against which the between-groups variance is compared to determine if there is a significant difference among the group means. 52) The numerator of the F-test reflects A) experimental, extraneous, and error variance. B) experimental and extraneous variance. C) error variance only. D) experimental variance. Answer: A Rationale: The numerator of the F-test includes both experimental and extraneous variance, along with error variance. It represents the variability among group means that is attributable to the effects of the independent variable as well as any other systematic sources of variance. 53) The numerator of the F-test is A) a measure based on within-groups error variation. B) the degrees of freedom. C) a measure based on between-groups variation. D) the sum of squares. Answer: C Rationale: The numerator of the F-test reflects a measure based on between-groups variation. It compares the variability among group means with the variability expected due to random error or within-groups variation. 54) F is a ratio of A) within-groups variation divided by between-groups variation. B) between-groups variation divided by within-groups variation. C) external validity divided by internal validity. D) internal validity divided by external validity. Answer: B Rationale: F is calculated as the ratio of between-groups variation divided by within-groups variation. This ratio determines whether the observed differences among group means are greater than what would be expected by chance alone. 55) Which effect is reflected in both the numerator and the denominator of the F-test? A) systematic error variance B) systematic effects C) degrees of freedom D) nonsystematic error variance Answer: D Rationale: Nonsystematic error variance, which represents random error or variability within groups, is reflected in both the numerator and the denominator of the F-test. It contributes to both the within-groups variance (denominator) and the between-groups variance (numerator). 56) Experimental variance, extraneous variance, and sampling error A) contribute to the between-groups variance. B) constitute the within-groups variance. C) determine the sample size. D) are particularly important at the correlational level. Answer: A Rationale: Experimental variance, extraneous variance, and sampling error contribute to the between-groups variance because they represent the variability among group means that is not attributable to the effects of the independent variable. Within-groups variance is mainly constituted by nonsystematic error variance. 57) Which of the following must be found in order to observe an effect of the independent variable in an experiment? A) high error variance B) high group means C) high between-group variance D) high standard deviations Answer: C Rationale: In order to observe an effect of the independent variable, there must be high between-group variance, indicating that the variability among group means is greater than what would be expected due to random error alone. 58) The numerator of the F-test can be expressed as A) systematic effects plus error variance. B) experimental variance plus extraneous variance. C) extraneous variance plus error variance. D) the sum of squares. Answer: A Rationale: The numerator of the F-test represents systematic effects (experimental and extraneous variance) plus error variance. It captures the variability among group means that is attributable to the effects of the independent variable and other systematic sources of variance. 59) The denominator of the F-test is A) N - 1. B) the sum of squares multiplied by the degrees of freedom. C) a measure based on between-groups variation. D) a measure based on within-groups error variation. Answer: D Rationale: The denominator of the F-test is a measure based on within-groups error variation. It reflects the variability of scores within each group or condition, serving as the baseline against which the between-groups variation is compared. 60) The denominator of the F-test reflects A) systematic effects plus error variance. B) error variance. C) experimental variance. D) extraneous variance. Answer: B Rationale: The denominator of the F-test represents the within-groups variance or error variance. It reflects the variability of scores within each group or condition, which serves as the baseline against which the between-groups variance is compared to determine if there is a significant difference among the group means. 61) The F-test compares ________ variation to ________ variation. A) unsystematic between-groups; systematic within-groups B) between-groups; within-groups C) systematic within-groups error; nonsystematic within-groups D) nonsystematic between-groups; systematic between-groups Answer: B Rationale: The F-test compares the variability between different groups (between-groups variation) to the variability within each group (within-groups variation) to determine if there are significant differences between the group means. 62) Analysis of variance uses A) only the between-groups variance. B) only the within-groups variance. C) both the within-groups variance and the between-groups variance. D) only the means and not the variance. Answer: C Rationale: Analysis of variance (ANOVA) assesses differences among group means by considering both the variability within groups (within-groups variance) and the variability between groups (between-groups variance). 63) Between-groups variance is comprised of both systematic effects and A) experimental variance. B) degrees of freedom. C) the variation due to the effects of the independent variables. D) the variation due to sampling error. Answer: D Rationale: Between-groups variance includes systematic effects, which are the effects of the independent variable, as well as nonsystematic effects, such as sampling error or random variability. 64) If all groups in an experiment have approximately the same mean, then A) the between-groups variance will be small. B) the degrees of freedom will be large. C) the within-groups variance will be large. D) the between-groups variance will be large. Answer: A Rationale: If all groups have similar means, there is less variability between groups, resulting in a smaller between-groups variance. 65) Whenever the F-ratio is near 1.00, it means that A) a mistake has been made in the computation. B) there are large systematic effects present. C) the experimental manipulation probably had the predicted effects. D) the between-groups variation is no larger than would be expected by chance alone. Answer: D Rationale: An F-ratio near 1.00 suggests that the variability between groups is similar to what would be expected due to chance alone, indicating that there are no significant differences between groups. 66) When would you conclude there is a causal effect in an experiment? A) when the systematic variance is high and error variance is low B) when both systematic and error variance are low C) when the error variance is greater than the systematic variance D) when the error variance has a positive effect on the mean of the experimental group Answer: A Rationale: A causal effect is more likely when there is high systematic variance (variation attributable to the independent variable) and low error variance (random variability not attributable to the independent variable). 67) An F-ratio of 1.0 signifies A) no error variance. B) no within-groups effects. C) no unsystematic effects. D) no systematic effects. Answer: D Rationale: An F-ratio of 1.0 indicates that the variability between groups is not significantly different from the variability within groups, suggesting that there are no systematic effects. 68) A researcher can evaluate the effectiveness of the manipulations of the independent variable by including A) a test for independence of groups. B) a variable check. C) a manipulation check. D) an F-test. Answer: C Rationale: A manipulation check assesses whether the independent variable has been successfully manipulated as intended, providing insight into the effectiveness of the experimental manipulation. 69) A general but important rule in experimentation is that each study is designed so as to A) control experimental variance, maximize extraneous variance, and control error variance. B) maximize experimental variance, control extraneous variance, and minimize error variance. C) maximize all variance except error variance. D) ignore error variance and maximize between-groups variation. Answer: B Rationale: Experimentation aims to maximize experimental variance (variation attributable to the independent variable), control extraneous variance (unwanted sources of variability), and minimize error variance (random variability not attributable to the independent variable) to ensure accurate and valid conclusions. 70) A manipulation check in an experiment A) assesses the independent variable. B) assesses the null hypothesis. C) is applied only in low-constraint research. D) assesses the dependent variable. Answer: A Rationale: A manipulation check assesses whether the independent variable has been manipulated as intended, ensuring that any observed effects can be attributed to the manipulation. 71) Experimental studies are designed to maximize ________ variance, control ________ variance, and minimize ________ variance A) experimental; extraneous; error B) extraneous; experimental; error C) extraneous; error; experimental D) experimental; error; extraneous Answer: A Rationale: Experimental studies aim to maximize experimental variance to detect the effects of the independent variable, control extraneous variance to ensure that observed effects are due to the manipulation, and minimize error variance to increase the accuracy of the findings. 72) In experimental studies, it is important to design experiments so that A) unsystematic error is increased. B) extraneous variance is maximized. C) experimental conditions are clearly different from each other. D) nonexperimental conditions are clearly different from each other. Answer: C Rationale: Experimental conditions should be clearly different from each other to ensure that any observed effects can be attributed to the manipulation of the independent variable rather than other factors. 73) An evaluation of whether the manipulation of the independent variable was effective is called a(n) A) effect check. B) manipulation check. C) operational check. D) outcome check. Answer: B Rationale: A manipulation check is used to assess whether the manipulation of the independent variable had the intended effect on participants before analyzing the results of the study. 74) Dr. Schmo is doing a study examining the effects of fear on midterm grades in a psychology course. He sets up three conditions (high fear, moderate fear, no fear). An appropriate manipulation check would be A) to give a test of fear to participants and compare the three groups. B) to give an alternative psychology midterm. C) to compare test scores between three groups. D) None of the above Answer: A Rationale: A manipulation check in this scenario would involve giving a test of fear to participants in each condition and comparing the results to ensure that the manipulation effectively induced different levels of fear across the groups. 75) A major goal of experimental design is to A) increase internal validity by increasing degrees of freedom. B) increase internal validity by decreasing degrees of freedom. C) decrease internal validity by controlling variance. D) increase internal validity by controlling variance. Answer: D Rationale: The major goal of experimental design is to increase internal validity by controlling for extraneous variables and minimizing error variance, which allows for more confident conclusions about the relationship between the independent and dependent variables. 76) To help determine if the conditions in a study truly differed A) the experimenter should reduce the sample size. B) at least three conditions need to be included. C) a manipulation check is included. D) a standard one-way ANOVA should be applied. Answer: C Rationale: A manipulation check helps determine if the conditions in a study truly differed by assessing whether the manipulation effectively influenced the independent variable as intended. 77) It is advisable in an experiment to A) include more than two levels of the independent variable. B) use nominal scales for dependent variable measurements. C) have no more than 30 participants in each group. D) have at least 50 participants in at least one of the groups. Answer: A Rationale: Including more than two levels of the independent variable increases the generalizability and robustness of the findings, allowing for a more comprehensive understanding of the relationship between the independent and dependent variables. 78) In an experiment, we need to A) maximize within-groups variability. B) minimize experimental variance. C) maximize experimental variance. D) minimize between-groups variance. Answer: C Rationale: Maximizing experimental variance increases the likelihood of detecting significant effects of the independent variable, providing stronger evidence for the relationship between the independent and dependent variables. 79) The researcher should attempt to arrange the experiment so as to control extraneous variance, minimize error variance, and A) minimize experimental variance. B) maximize experimental variance. C) combine experimental variance with the total sum of squares. D) ignore experimental variance. Answer: B Rationale: In addition to controlling extraneous and error variance, researchers should aim to maximize experimental variance to increase the sensitivity of the study to detect effects of the independent variable. 80) A manipulation check is A) necessary at the naturalistic level of research. B) not needed at the experimental level. C) often too difficult to carry out. D) appropriate only at the experimental level. Answer: D Rationale: A manipulation check is appropriate at the experimental level to ensure that the manipulation effectively influences the independent variable as intended, providing confidence in the validity of the experimental results. 81) A manipulation check on the independent variable might consist of A) a simple self-report measure of anxiety. B) giving participants false feedback after the experiment. C) verifying demographic information provided by participants. D) nonrandom assignment of participants to groups. Answer: A Rationale: A manipulation check assesses whether the independent variable manipulation has the intended effect on participants. Option A) a simple self-report measure of anxiety directly evaluates the impact of the independent variable (manipulation) on the participants, making it a suitable choice for a manipulation check. 82) Making sure the experimental and control groups are as similar as possible at the start of the experiment and that they are treated in exactly the same way except for the independent variable manipulation controls for A) error variance. B) extraneous variance. C) experimental effects. D) experimental variance. Answer: B Rationale: Ensuring that experimental and control groups are similar at the start and treated the same way except for the independent variable manipulation helps control for extraneous variance, which refers to any sources of variability in the data other than the independent variable. Thus, option B) extraneous variance is the correct choice. 83) A manipulation check is A) often used but rarely needed. B) used to evaluate the effectiveness of a manipulation. C) far too difficult to use routinely. D) not recommended by the text's authors. Answer: B Rationale: A manipulation check is used to assess the effectiveness of the independent variable manipulation. It ensures that the manipulation has the intended effect on participants. Thus, option B) used to evaluate the effectiveness of a manipulation is the correct choice. 84) Which of the following is NOT a way of controlling extraneous variance? A) random assignment of participants B) building potential confounding variables into the experiment as an additional independent variable C) eliminating confounding variables by selecting participants who are as homogeneous as possible on that variable D) ad hoc sampling Answer: D Rationale: Ad hoc sampling refers to a non-systematic or arbitrary method of selecting participants, which does not control extraneous variance effectively. Options A, B, and C all involve methods to control extraneous variance, such as random assignment, incorporating potential confounding variables into the experiment, and selecting homogeneous participants, respectively. 85) In experimental research, extraneous variables are always A) between-group variables. B) within-group variables. C) organismic variables. D) response variables. Answer: A Rationale: Extraneous variables are factors other than the independent variable that could influence the dependent variable. In experimental research, extraneous variables are typically between-group variables because they can differ between the experimental and control groups, potentially confounding the results. Thus, option A) between-group variables is the correct choice. 86) Extraneous variables have their effects A) only on individuals. B) on whole groups. C) randomly among individuals. D) on experimenters. Answer: B Rationale: Extraneous variables can affect the entire group of participants in an experiment, not just individuals. These variables introduce variability into the results and can potentially confound the relationship between the independent and dependent variables. Thus, option B) on whole groups is the correct choice. 87) When a researcher builds in additional independent variables to control for extraneous variables, the design is called a A) manipulated design. B) complicated design. C) factorial design. D) correlational design. Answer: C Rationale: A factorial design involves manipulating more than one independent variable to examine their effects on the dependent variable. When additional independent variables are included to control for extraneous variables, it's termed a factorial design. Thus, option C) factorial design is the correct choice. 88) Control in experimentation refers to control of A) experimental variance. B) extraneous variance. C) error variance. D) All of the above Answer: D Rationale: Control in experimentation refers to managing and minimizing sources of variability, including experimental variance, extraneous variance, and error variance. Thus, option D) All of the above is the correct choice. 89) In experimentation, the term control refers to A) control of variance. B) the reduction of the number of participants in a condition. C) the increase in individual difference to obtain more variation. D) random assignment of participants to conditions only. Answer: A Rationale: Control in experimentation involves managing and minimizing sources of variability, which is primarily achieved by controlling variance. This ensures that observed effects can be attributed to the independent variable rather than extraneous factors. Thus, option A) control of variance is the correct choice. 90) Within-subjects designs reduce error variance by A) controlling conditions of measurement. B) randomization. C) eliminating individual differences. D) adding more participants. Answer: C Rationale: Within-subjects designs involve each participant experiencing all conditions of the experiment, thereby controlling for individual differences between participants. This reduces error variance, which is variability in the dependent variable that is not due to the independent variable. Thus, option C) eliminating individual differences is the correct choice. 91) What is usually the major contributor to error variance? A) group size B) unreliable measurement C) individual differences D) high means Answer: C Rationale: Individual differences among participants typically contribute significantly to error variance in experiments. These differences can stem from various factors such as personality traits, abilities, experiences, and other characteristics unique to each participant. 92) Which of the following is accomplished in a within-subjects design? A) reduction of error variance B) increase in individual differences C) improvement of external validity D) increase in the alpha level Answer: A Rationale: Within-subjects designs involve each participant experiencing all experimental conditions, which allows researchers to control for individual differences and thereby reduce error variance compared to between-subjects designs. 93) Carefully controlling measurement conditions and developing reliable measurement instruments aids in minimizing A) extraneous variance. B) error variance. C) systematic effects. D) experimental variance. Answer: B Rationale: Error variance refers to the variability in scores that is not due to the variables being studied but rather to random fluctuations or measurement errors. By controlling measurement conditions and ensuring reliable measurement instruments, researchers can minimize error variance. 94) The use of within-subjects designs and the use of reliable measuring instruments minimize A) extraneous variance. B) error variance. C) experimental effect. D) experimental variance. Answer: B Rationale: Both within-subjects designs and reliable measurement instruments help minimize error variance by controlling for individual differences and reducing measurement error, respectively. 95) The value of F will increase if A) extraneous variance increases. B) error variance increases. C) experimental variance decreases. D) extraneous variance decreases. Answer: A Rationale: The F-ratio in ANOVA compares the variance between groups to the variance within groups. If extraneous variance increases, it contributes to the within-group variance, leading to a larger F-value. 96) In an ANOVA, we try to A) maximize experimental variance and within-groups variance. B) minimize error variance and control extraneous variance. C) minimize both error variance and experimental variance. D) control extraneous variance and maximize error variance. Answer: B Rationale: In ANOVA, the goal is to minimize error variance while controlling for extraneous variance. This is achieved by ensuring that the variance between groups (experimental variance) is greater than the variance within groups (error variance). 97) An experiment ______ manipulation check(s). A) can have two B) can have no more than one C) never needs a D) must have at least two Answer: A Rationale: It is common for experiments to include multiple manipulation checks to ensure that the intended manipulation has occurred as expected and to assess its effectiveness. 98) Extraneous variables A) are between-groups variables. B) are necessary in experiments. C) affect the statement of the problem. D) need to be built into the study by the researcher. Answer: A Rationale: Extraneous variables are variables other than the independent variable that may affect the dependent variable. They are often inherent in experiments and can potentially confound the results if not controlled for. 10.2 Nonexperimental Approaches 1) Which of the following is an experimental design? A) single-group, posttest-only design B) single-group, pretest-posttest design C) ex post facto design D) None of the above Answer: D Rationale: Experimental designs typically involve manipulation of an independent variable and random assignment to conditions, none of which are present in the options provided. 2) The design in which a researcher observes current behavior and attempts to relate it causally to earlier factors is a(n) A) single-group, posttest-only design. B) ad hoc design. C) ex post facto design. D) single-group, pretest-posttest design. Answer: C Rationale: Ex post facto designs involve observing and analyzing existing differences or relationships without manipulation by the researcher, attempting to establish causal relationships between variables based on past events or conditions. 3) A researcher measures prisoners on childhood physical abuse and notices high levels of abuse. He then concludes that abuse leads people to commit crimes. This is an example of a(n) A) single-group, pretest-posttest design. B) single-group, posttest-only design. C) ad hoc design. D) ex post facto design. Answer: D Rationale: Ex post facto design involves observing and analyzing the effects of naturally occurring events or situations without manipulation by the researcher. In this scenario, the researcher observes the presence of childhood physical abuse (the independent variable) and its association with criminal behavior (the dependent variable) without any manipulation. Therefore, it aligns with the characteristics of an ex post facto design. 4) ________ studies are commonly used procedures, but are NOT experiments. A) Randomized, posttest-only, control-group B) Factorial design C) Post hoc D) Ex post facto Answer: D Rationale: Ex post facto studies are observational in nature and do not involve experimental manipulation of variables. Instead, they examine the effects of variables that have occurred naturally or were pre-existing. 5) The conclusions reached by ex post facto designs are A) scientifically valid because all confounding variables are controlled. B) not scientifically valid although all confounding variables are controlled. C) not scientifically valid because confounding variables are not controlled. D) scientifically valid because all extraneous variables are controlled. Answer: C Rationale: Ex post facto designs lack the experimental control necessary to establish causal relationships because researchers cannot manipulate independent variables. As a result, confounding variables cannot be controlled, which compromises the scientific validity of the conclusions drawn from such designs. 6) A researcher measures prisoners on childhood physical abuse and notices high levels. He then concludes that abuse leads people to commit crimes. This is an example of an ex post facto design. These conclusions are A) scientifically valid because confounding variables are controlled. B) not scientifically valid although all confounding variables are controlled. C) not scientifically valid because confounding variables are not controlled. D) scientifically valid because all extraneous variables are controlled. Answer: C Rationale: The conclusion drawn from the ex post facto design scenario is not scientifically valid because confounding variables, such as other environmental factors or genetic predispositions, are not controlled for. Therefore, the observed association between childhood physical abuse and criminal behavior cannot be definitively attributed to a causal relationship. 7) Ex post facto designs are useful in A) testing causal hypotheses. B) proving causal hypotheses. C) eliminating rival hypotheses. D) generating causal hypotheses. Answer: D Rationale: Ex post facto designs are useful for generating causal hypotheses by observing naturally occurring relationships between variables. However, they do not provide conclusive evidence of causation due to the lack of experimental manipulation and control over confounding variables. 8) If a therapist treats a 28-year-old client for depression and attempts to relate the depression causally to the fact that the client failed kindergarten twice, the therapist would be employing A) an ex post facto research design. B) a valid method of establishing causation. C) high-constraint research methods. D) a manipulation of the independent variable. Answer: A Rationale: The therapist would be employing an ex post facto research design by attempting to establish a causal relationship between the client's past experience of failing kindergarten and their current depression without experimental manipulation of variables. 9) One of the chief weaknesses of an ex post facto procedure is that A) it is only valid in research on children. B) no dependent variable can be manipulated. C) the researcher is unable to eliminate rival hypotheses. D) there are no confounding variables. Answer: C Rationale: A chief weakness of ex post facto procedures is the inability to eliminate rival hypotheses due to the lack of experimental control over variables. Confounding variables may exist and influence the relationship between the observed variables, making it challenging to establish causal relationships. 10) Why are ex post facto studies weak? A) Too few participants are used. B) They require so long to run that responses are no longer representative. C) Independent variables cannot be manipulated. D) Response variables cannot be measured. Answer: C Rationale: Ex post facto studies are weak because independent variables cannot be manipulated, limiting researchers' ability to establish causal relationships between variables. 11) Ex post facto studies A) can tell us nothing. B) have value in testing causal hypotheses. C) have value in generating causal hypotheses. D) are the only studies possible in clinical settings. Answer: C Rationale: Ex post facto studies have value in generating causal hypotheses by observing naturally occurring relationships between variables. However, they cannot definitively establish causation due to the lack of experimental control. 12) An ex post facto study A) cannot generate causal hypotheses. B) cannot answer a research question. C) can generate causal hypotheses. D) can test causal hypotheses. Answer: C Rationale: An ex post facto study can generate causal hypotheses by observing associations between variables. However, it cannot definitively establish causation due to the lack of experimental manipulation and control. 13) A researcher wants to look at the effects of "stress endurance treatment" on self-esteem in cancer patients. The researcher has 50 cancer patients attend "stress endurance treatment" sessions once a week. At the end of the 8-week treatment, participants are measured on self-esteem. This is an example of a(n) A) ex post facto design. B) ad hoc design. C) single-group, posttest-only design. D) longitudinal design. Answer: C Rationale: This is a single-group, posttest-only design because there's only one group of participants measured on the dependent variable (self-esteem) after the treatment without any comparison group or pretest. 14) The single-group, posttest-only design A) cannot be used in human research. B) is one of the strongest designs possible. C) is weak because there is no manipulation of a variable. D) includes a manipulation of an independent variable. Answer: D Rationale: In a single-group, posttest-only design, there is still a manipulation of the independent variable (in this case, the "stress endurance treatment"), even though there is no control group. Participants are exposed to the treatment, allowing for the assessment of its effects. 15) Which of the following does the single-group, posttest-only design control for? A) maturation B) placebo effects C) history D) None of the above Answer: D Rationale: The single-group, posttest-only design does not control for any threats to internal validity since there's no comparison group or pretest. Therefore, it does not control for maturation, placebo effects, or history. 16) In a single-group, posttest-only study, an observed difference A) cannot be a placebo effect. B) might be a placebo effect. C) is strong evidence for a causal relationship. D) is almost always going to be statistically significant. Answer: B Rationale: In this design, without a comparison group, it's difficult to determine if the observed difference is due to the treatment or other factors. Therefore, the observed difference might be due to placebo effects or other confounding variables. 17) A difference that is produced only by an expectation of an effect A) is impossible in experimental designs. B) is a placebo effect. C) is routine in experimental designs. D) cannot be controlled, but it is rarely a significant problem. Answer: B Rationale: A difference produced only by an expectation of an effect is termed a placebo effect. It can occur in experimental designs, especially in designs lacking a control group like the single-group, posttest-only design. 18) When one group of participants is measured before and after the manipulation of the independent variable, we have a(n) A) ex post facto design. B) ad hoc design. C) single-group, pretest-posttest design. D) pretest-posttest, control-group design. Answer: C Rationale: In a single-group, pretest-posttest design, participants are measured on the dependent variable both before and after the manipulation of the independent variable within the same group. There is no control group in this design. 19) A researcher wants to look at the effects of "stress endurance treatment" on self-esteem in cancer patients. The researcher measures 50 cancer patients on self-esteem. The researcher then has all the participants attend "stress endurance treatment" sessions once a week. At the end of the 8-week treatment, participants are again measured on self-esteem. This is an example of a(n) A) ex post facto design. B) ad hoc design. C) single-group, posttest-only design. D) single-group, pretest-posttest design. Answer: D Rationale: This is a single-group, pretest-posttest design because participants are measured on the dependent variable (self-esteem) both before and after the treatment. There's no comparison group in this design. 20) If a researcher administered a mood scale to a sample of anxious adults, removed their televisions for two months, and again administered the mood scale after two months of no TV, the researcher would be employing A) a single-group, posttest-only design. B) an ex post facto design. C) a single-group, pretest-posttest design. D) a pretest-posttest, natural control-group design. Answer: C Rationale: This scenario describes a single-group, pretest-posttest design where participants are measured on the dependent variable (mood) both before and after the manipulation (removing TVs). There's no comparison group in this design. 21) Which of the following would the single-group, pretest-posttest design control for? A) history B) maturation C) regression to the mean D) None of the above Answer: D Rationale: The single-group, pretest-posttest design does not control for any threats to internal validity since there's no comparison group. Therefore, it does not control for history, maturation, or regression to the mean. 22) To look at maturation, developmental psychologists frequently use A) longitudinal designs. B) latitudinal designs. C) Solomon four-group designs. D) single-group, posttest-only designs. Answer: A Rationale: Longitudinal designs involve studying the same participants over an extended period, making them suitable for investigating developmental changes and maturation effects. 23) The pretest-posttest, natural control-group design differs from an experimental design in that A) participants are not randomly assigned to groups. B) it is more natural and therefore more valid. C) it does not control for history and instrumentation. D) it does not control for history and regression to the mean. Answer: A Rationale: In the pretest-posttest, natural control-group design, participants are not randomly assigned to groups, which is a key characteristic of experimental designs. This lack of random assignment can lead to potential biases in group composition and threatens the internal validity of the study. 24) A research design in which multiple measures are taken over the course of a study is called a A) frequent measures design. B) multiple measures design. C) time-series design. D) multilevel, randomized between-subjects design. Answer: C Rationale: Time-series designs involve the repeated measurement of the same variable over time, allowing researchers to observe changes and trends in behavior or phenomena across multiple time points. 25) In a pretest-posttest, natural control-group design, there is ________ assignment of participants. A) random B) matching C) no random D) systematized random Answer: C Rationale: In this design, participants are not randomly assigned to groups but rather allocated naturally or based on existing conditions, hence there is no random assignment involved. 26) A researcher decides to study the effects of dance therapy on self-esteem in emotionally disturbed adolescents. One residential program consents to try the dance therapy treatment, whereas another similar program refuses to try dance therapy, but allows the researcher to measure self-esteem. Self-esteem is measured before and after treatment in both groups. This is an example of a A) multilevel, pretest-posttest control-group design. B) pretest-posttest, natural control-group design. C) randomized, pretest-posttest, control-group design. D) multilevel, randomized, pretest-posttest, between-subjects design. Answer: B Rationale: In this scenario, the researcher is not manipulating the assignment of participants to treatment conditions; instead, they are taking advantage of existing conditions, making it a pretest-posttest, natural control-group design. 27) If a researcher administered a mood scale to two preexisting groups of anxious adults, removed the TV sets from one of the groups for two months, and again administered the mood scale to both groups, the researcher would be employing A) an ex post facto design. B) a single-group, posttest-only design. C) a single-group, pretest-posttest design. D) a pretest-posttest, natural control-group design. Answer: D Rationale: In this scenario, the researcher is not randomly assigning participants to groups but rather utilizing existing groups and conditions, making it a pretest-posttest, natural control-group design. 28) In a pretest-posttest, natural control-group design, the experimental and control groups are ________ at the beginning of the experiment. A) equivalent B) not equivalent C) matched D) Could be either A or B Answer: D Rationale: The equivalence of groups at the beginning of the experiment in a pretest-posttest, natural control-group design can vary depending on the natural allocation of participants, hence it could be either equivalent or not equivalent. 29) A serious weakness of the pretest-posttest, natural control-group design is that A) the two groups may be statistically different from each other at the start of the study. B) the two groups may be statistically equivalent at the start of the study. C) experimenter effects cannot be prevented. D) there is no control for effects due to history or maturation. Answer: A Rationale: Since participants are not randomly assigned to groups in this design, there's a risk that the groups may differ systematically at the beginning of the study, potentially confounding the interpretation of results. 30) The major difference between the control groups of the pretest-posttest, natural control group design and the randomized, posttest-only, control-group design is that A) in the latter, participants are randomly assigned to groups. B) in the former, the people in the control group are aware of the research hypothesis. C) in the latter, participants are only assigned randomly to the experimental group, but not the control group. D) there is no real difference between the two designs. Answer: A Rationale: The major distinction is that in the randomized, posttest-only, control-group design, participants are randomly assigned to groups, ensuring equivalence between groups at the outset, whereas in the pretest-posttest, natural control-group design, participants are not randomly assigned. 31) History, maturation, and regression to the mean can be controlled by including proper A) control groups B) experimental groups. C) factorials. D) instrumentation. Answer: A Rationale: Proper control groups help to control for extraneous variables such as history, maturation, and regression to the mean, thereby enhancing the internal validity of the study. 32) Including proper control groups helps to A) control experimenter effects. B) randomize the effects of the dependent variable. C) eliminate confounding due to subject effects. D) control history, maturation, and regression to the mean. Answer: D Rationale: Control groups allow researchers to account for potential confounding variables and sources of error, such as history, maturation, and regression to the mean, thereby strengthening the validity of the study's findings. 33) Random assignment of participants to groups helps reduce A) attrition. B) regression to the mean. C) threats to internal validity from attrition and regression to the mean. D) threats to construct validity. Answer: C Rationale: Random assignment of participants to groups helps reduce threats to internal validity from attrition and regression to the mean by ensuring that any individual differences or characteristics that may affect the outcome variables are evenly distributed across the experimental and control groups, thus minimizing the potential impact on the results. 34) In an experiment, it is essential that the groups be equivalent on ________ at the start of the study. A) the independent variable B) the dependent measures C) participant numbers D) both the independent and dependent variables Answer: B Rationale: In an experiment, it is essential that the groups be equivalent on the dependent measures at the start of the study to ensure that any differences observed between the groups post-intervention can be attributed to the manipulation of the independent variable rather than pre-existing differences in the dependent measures. 35) Two critical factors used to distinguish experimental designs from most nonexperimental designs are A) randomization and equal numbers of participants. B) elimination of all confounds and randomization. C) control groups and randomization. D) sophisticated data analysis and control groups. Answer: C Rationale: Two critical factors used to distinguish experimental designs from most nonexperimental designs are control groups and randomization. Experimental designs involve the manipulation of an independent variable and the use of control groups to establish causality, whereas nonexperimental designs typically lack these features. 36) Random assignment A) increases confidence that the groups are the same at the start of the study. B) is the best way to increase statistical power. C) is difficult to include in experimental designs. D) maximizes experimental variance. Answer: A Rationale: Random assignment increases confidence that the groups are the same at the start of the study by ensuring that any individual differences or characteristics that may affect the outcome variables are evenly distributed across the experimental and control groups, thus enhancing the internal validity of the study. 37) The two characteristics that distinguish experimental designs from nonexperimental designs are A) randomization and sample size. B) sample size and control groups. C) control groups and level of measurement. D) control groups and randomization. Answer: D Rationale: The two characteristics that distinguish experimental designs from nonexperimental designs are control groups and randomization. Experimental designs involve manipulation of an independent variable and the use of control groups to establish causality, whereas nonexperimental designs typically lack these features. 1) In controlling variance, a researcher increases A) generalizability. B) external validity. C) reliability. D) internal validity. Answer: D Rationale: In controlling variance, a researcher increases internal validity by reducing the impact of extraneous variables on the dependent variable, thus enhancing the ability to draw causal inferences. 2) Random assignment of participants to groups increases the probability A) that all participants will finish the experiment. B) that the groups are equivalent at the beginning of the study. C) that the groups are equivalent at the end of the study. D) that the groups are different from one another. Answer: B Rationale: Random assignment of participants to groups increases the probability that the groups are equivalent at the beginning of the study by ensuring that any individual differences or characteristics that may affect the outcome variables are evenly distributed across the experimental and control groups. 3) Which of the following is an experimental design? A) randomized, posttest-only design B) single-group, pretest-posttest design C) single group, posttest only design D) pretest-posttest, natural control-group design Answer: A Rationale: The randomized, posttest-only design is an experimental design because it involves manipulation of an independent variable (randomization) and the use of a control group to establish causality. 4) In order to test the effects of the 1988 heat wave on worker productivity, 48 machinists were randomly assigned to two groups of 24 machinists each. Each group was tested at a different room temperature (cool and hot) using dependent measures of number of parts produced and accuracy. What type of design does this study represent? A) a single-group, pretest-posttest design B) a Solomon four-group design C) a multilevel, completely randomized, between-subjects design D) a randomized, posttest-only, control-group design Answer: D Rationale: This study represents a randomized, posttest-only, control-group design because participants were randomly assigned to different conditions (cool and hot room temperatures) and tested on dependent measures post-intervention, with the inclusion of a control group. 5) In the randomized, posttest-only, control-group design, external validity is protected by A) random selection of the sample. B) random assignment of participants to groups. C) use of a control group. D) None of the above Answer: A Rationale: In the randomized, posttest-only, control-group design, external validity is protected by random selection of the sample, which helps ensure that the findings can be generalized to the population from which the sample was drawn. 6) Threats to internal validity from regression to the mean in randomized, posttest-only, control-group designs are controlled by A) nonrandom assignment of participants. B) random assignment of participants to groups. C) controlling for experimental effect. D) Both A and C Answer: B Rationale: Random assignment of participants to groups in randomized, posttest-only, control-group designs helps to mitigate the effects of regression to the mean, ensuring that any observed differences between groups can be more confidently attributed to the treatment rather than to natural fluctuations in participant characteristics. 7) A randomized, pretest-posttest, control-group design is A) an experimental design. B) not an experimental design. C) is not completely randomized. D) Both B and C Answer: A Rationale: A randomized, pretest-posttest, control-group design is considered an experimental design because it involves the random assignment of participants to different experimental conditions, allowing researchers to make causal inferences about the effects of the independent variable on the dependent variable. 8) By pretesting the two groups on the dependent variable in a randomized, pretest-posttest, control-group design, we A) rule out variance on all variables of all groups. B) test for initial equivalence on the dependent variable. C) eliminate confounding. D) None of the above. Answer: B Rationale: Pretesting the two groups on the dependent variable helps to ensure that they are initially equivalent on that variable, reducing the possibility that observed differences posttreatment are due to preexisting differences between groups rather than the treatment itself. 9) The randomized pretest-posttest, control-group design is an improvement over the randomized posttest-only, control-group design because A) the former adds an additional control group. B) the latter employs randomization only at the time of the posttest. C) the former adds a pretreatment measurement of the independent variable. D) the former adds a pretreatment measurement of the dependent variable. Answer: D Rationale: The inclusion of a pretest measurement of the dependent variable in the randomized pretest-posttest, control-group design helps to control for individual differences in baseline levels of the dependent variable, increasing the internal validity of the study. 10) In the multilevel, completely-randomized, between-subjects design, participants are randomly assigned to A) one condition. B) two conditions. C) three or more conditions. D) None of the above Answer: C Rationale: In the multilevel, completely-randomized, between-subjects design, participants are randomly assigned to three or more conditions, allowing researchers to investigate the effects of multiple levels of an independent variable on the dependent variable. 11) In a study using the multilevel, completely-randomized between-subjects design, 48 rats were randomly assigned to six groups of eight rats each. Each group was tested at a different level of ambient noise. Maze running speed and accuracy were measured. The independent variable in this study was A) the number of rats. B) speed. C) accuracy. D) ambient noise level. Answer: D Rationale: The independent variable in this study is the ambient noise level, as it is manipulated by the researcher to assess its effects on maze running speed and accuracy. 12) In a study using the multilevel, completely-randomized between-subjects design, 48 rats were randomly assigned to six groups of eight rats each. Each group was tested at a different level of ambient noise. Maze running speed and accuracy were measured. A dependent variable in this study was A) the number of rats. B) speed. C) ambient noise level. D) None of the above. Answer: B Rationale: The dependent variable in this study is maze running speed, as it is measured to assess the impact of varying levels of ambient noise on rat performance. 13) In the multilevel, completely-randomized, between-subjects design, participants are A) randomly assigned to three or more conditions. B) randomly assigned to two conditions. C) always tested on a pretest measure. D) always assigned to groups with equal numbers of participants. Answer: A Rationale: In the multilevel, completely-randomized, between-subjects design, participants are randomly assigned to three or more conditions, allowing researchers to investigate the effects of multiple levels of an independent variable on the dependent variable. 14) The study first introduced in Chapter 9 that was concerned with the effects of varying levels of room temperature on typing speed and accuracy employed which type of design? A) a randomized, posttest-only, control-group design B) a multilevel, completely randomized, between-subjects design C) a Solomon four-group design D) a single-group, posttest-only design Answer: B Rationale: The study employed a multilevel, completely randomized, between-subjects design by randomly assigning typists to different groups exposed to varying room temperatures to assess their effects on typing speed and accuracy. 15) In order to test the effects of room temperature on worker productivity, 48 typists were randomly assigned to six groups of eight typists each, and each group was tested at a different room temperature (the independent variable) using dependent measures of typing speed and accuracy. What type of design does this study represent? A) an ex post facto design B) a Solomon four-group design C) a multilevel, completely-randomized, between-subjects design D) a multilevel, randomized within-subjects design Answer: C Rationale: This study represents a multilevel, completely-randomized, between-subjects design, as participants are assigned to different conditions of the independent variable (room temperature) and tested on dependent measures (typing speed and accuracy) across these conditions. 16) The Solomon four-group design was developed in an attempt to A) control possible interaction effects of the pretest and the manipulation. B) allow more levels of the independent variable. C) allow more groups to be tested at the same time. D) control possible interaction effects of the pretest and posttest measures. Answer: A Rationale: The Solomon four-group design was developed to control possible interaction effects between the pretest and the manipulation. By including both pretest and posttest measures in both experimental and control groups, this design allows researchers to assess the effect of the manipulation while controlling for any preexisting differences between groups. 17) The Solomon four-group design combines the A) randomized, pretest-posttest, control-group design and the randomized, posttest-only, control-group design. B) randomized, pretest-posttest, control-group design with the multilevel, completely-randomized, between-subjects design. C) multilevel, completely-randomized, between-subjects design with the posttest-only, control-group design. D) None of the above Answer: A Rationale: The Solomon four-group design combines elements of both the randomized, pretest-posttest, control-group design and the randomized, posttest-only, control-group design. It includes two experimental groups and two control groups, each with both pretest and posttest measures, allowing for a more robust assessment of the treatment effect while controlling for potential pretest sensitization. 18) A disadvantage of using the Solomon four-group design is that A) it is not useful in situations in which an interaction is suspected. B) it requires the resources of two experiments. C) the data are difficult to analyze and interpret. D) it is only useful in preliminary testing of basic hypotheses. Answer: B Rationale: A disadvantage of the Solomon four-group design is that it requires the resources of two experiments due to its complex nature. This can increase the cost and time required for conducting the study, making it less practical in certain research settings. 19) Free random assignment of participants takes place in A) independent-groups designs. B) correlated-groups designs. C) matched-groups designs. D) None of the above Answer: A Rationale: Free random assignment of participants takes place in independent-groups designs, where participants are assigned to different groups based on chance. This helps ensure that each group is equivalent at the outset of the experiment, reducing the likelihood of systematic biases affecting the results. 20) Independent-groups designs are A) correlated designs. B) repeated measures designs. C) between-subjects designs. D) translational designs. Answer: C Rationale: Independent-groups designs are between-subjects designs where different participants are assigned to different experimental conditions or groups. Each participant experiences only one level of the independent variable, allowing for comparisons between groups. 21) In independent-groups designs, A) random assignment is optional. B) all participants are matched. C) the same participants are in each group. D) different participants are in each group. Answer: D Rationale: In independent-groups designs, different participants are assigned to each group. This ensures that any differences observed between groups are due to the experimental manipulation rather than preexisting differences between individuals. 10.4 Analysis of Variance 1) Appropriate statistical methods of analysis are selected on the basis of A) the level of measurement of the independent variable. B) whether the design was completely randomized. C) the level of measurement of the dependent variable. D) the level of sophistication of the researcher. Answer: C Rationale: Appropriate statistical methods of analysis are selected based on the level of measurement of the dependent variable. Different statistical tests are used for nominal, ordinal, interval, and ratio data. 2) The chief disadvantage of the t-test is that A) it evaluates only the variance and not the means. B) it is difficult to apply. C) it can only be used when there are three or more groups. D) it can only compare two groups at a time. Answer: D Rationale: The chief disadvantage of the t-test is that it can only compare two groups at a time. This limits its applicability in situations where more than two groups need to be compared. 3) The analysis of variance (ANOVA) is required in studies in which A) there are more than two groups to compare. B) the data are nominal. C) the data are ordered. D) there are only two groups to compare. Answer: A Rationale: The analysis of variance (ANOVA) is required in studies where there are more than two groups to compare. It allows for the simultaneous comparison of multiple group means, providing a more comprehensive assessment of group differences. 4) If all groups in an experiment have approximately the same mean, between-groups variance will be A) large. B) small. C) equal. D) None of the above Answer: B Rationale: If all groups in an experiment have approximately the same mean, between-groups variance will be small. This indicates that the groups are similar in terms of the dependent variable, reducing the likelihood of significant differences between groups. 5) Which of the following is true in the one-way ANOVA? A) The total sum of squares = between-groups sum of squares plus within-groups sum of squares. B) The total sum of squares = between-group sum of squares divided by within-groups sum of squares. C) The total sum of squares = within-groups sum of squares minus between-groups sum of squares. D) None of the above Answer: A Rationale: In one-way ANOVA, the total sum of squares (SS Total) equals the sum of squares between groups (SS Between) plus the sum of squares within groups (SS Within). This relationship is fundamental to understanding the partitioning of variance in ANOVA. 6) Analysis of variance uses A) within-groups variance. B) between-groups variance. C) extraneous variance. D) Both A and B Answer: D Rationale: Analysis of variance (ANOVA) utilizes both within-groups variance and between-groups variance to assess differences among group means. Within-groups variance measures variability within each group, while between-groups variance measures variability between group means. 7) The total sum of squares in a one-way ANOVA is partitioned into A) the between-groups variance and the within-groups variance. B) degrees of freedom and error variance. C) the between-groups sum of squares and the within-groups sum of squares. D) the between-groups sum of squares and the mean square due to error. Answer: C Rationale: In a one-way ANOVA, the total sum of squares (SS Total) is partitioned into the sum of squares between groups (SS Between) and the sum of squares within groups (SS Within), reflecting the variance attributable to group differences and the residual variance within groups, respectively. 8) In doing an ANOVA, dividing each of the sums of squares by the appropriate degrees of freedom will yield A) the average deviation from the mean. B) the F-ratio. C) the probability value. D) the mean squares. Answer: D Rationale: Dividing each sum of squares by its corresponding degrees of freedom yields the mean squares (MS), which are then used to calculate the F-ratio in ANOVA. The F-ratio compares the variability between groups to the variability within groups. 9) The F-test was originated by A) Sir Ronald Fisher. B) B.F. Skinner. C) Hans Eysenck. D) Sir Francis Bacon. Answer: A Rationale: The F-test was originated by Sir Ronald Fisher, a prominent statistician known for his contributions to experimental design and statistical inference. 10) The statistical significance of the ANOVA is based on the A) Fisher-Calkin test. B) t-test. C) Pearson product-moment correlation. D) F-test. Answer: D Rationale: The statistical significance of ANOVA is assessed using the F-test, which compares the variability between group means to the variability within groups. 11) The F-test represents the ratio of ________ to the ________. A) mean square due to error; between-groups mean square B) between-groups mean square; within-groups mean square C) between-groups mean square; degrees of freedom D) the degrees of freedom; sum of squares Answer: B Rationale: The F-test in ANOVA represents the ratio of the mean square between groups to the mean square within groups. This ratio evaluates whether the differences between group means are greater than would be expected by chance. 12) The F-test for a one-way ANOVA can be described in the following way; A) The F is equal to mean square between-groups divided by mean square within-groups. B) The F is equal to mean square between-groups. C) The F is equal to mean square between-groups multiplied by mean square within-groups. D) The F is equal to mean square multiplied by + or - 2.00. Answer: A Rationale: The F-test for a one-way ANOVA is calculated by dividing the mean square between groups by the mean square within groups, yielding the F-ratio. This ratio is used to determine the statistical significance of the group differences. 13) If the p-value for an F-test is less than the alpha level chosen in the experimental design phase, you should A) reject the null hypothesis and conclude that there is a significant difference between groups. B) reject the null hypothesis and conclude that there is no significant difference between groups. C) accept the null hypothesis and conclude that there is a significant difference between groups. D) accept the null hypothesis and conclude that there is no significant difference between groups. Answer: A Rationale: If the p-value for an F-test is less than the chosen alpha level (typically 0.05), it indicates that the observed differences between group means are statistically significant. Therefore, the null hypothesis is rejected, and it is concluded that there is a significant difference between groups. 14) A researcher used SPSS for Windows to perform an ANOVA for an experiment she conducted. In the design phase of the study, she decided to use an alpha level of .05. She should reject the null hypothesis and conclude that there is a significant difference between groups if the p-value is A) .10 B) 1.0 C) .05 D) .50 Answer: C Rationale: In hypothesis testing, if the p-value is less than the chosen alpha level (0.05 in this case), the null hypothesis is rejected. Therefore, if the p-value is less than 0.05, the researcher should reject the null hypothesis and conclude that there is a significant difference between groups. 15) The researcher evaluates the size of the F-ratio by A) comparing it with equivalent t values. B) comparing it with other F values used in the past. C) comparing its p value against the alpha level. D) consulting standards for scientific publication. Answer: C Rationale: Option C is correct because the size of the F-ratio is typically assessed by comparing its associated p-value against the predetermined alpha level. If the p-value is lower than the alpha level, it indicates that the observed F-ratio is statistically significant. 16) Between-groups variance is a measure of both systematic factors that affect the groups differently and variation due to sampling error. Systematic factors include A) observer bias B) experimental variance C) extraneous variance D) Both B and C Answer: D Rationale: Options B and C are correct because between-groups variance includes both experimental variance (systematic factors that affect groups differently) and extraneous variance (variation due to factors other than the independent variable), making option D the correct choice. 17) If there are no systematic between-groups differences, the F-ratio should have a value of approximately A) 9.00. B) -1.00. C) 1.00. D) 0. Answer: C Rationale: Option C is correct because if there are no systematic between-groups differences, it implies that the numerator (between-groups variance) and denominator (within-groups variance) are approximately equal, leading to an F-ratio close to 1.00. 18) The most important method for decreasing the error term is to A) decrease the sample size. B) hold the independent variable constant. C) increase the number of dependent variables. D) increase sample size. Answer: D Rationale: Option D is correct because increasing the sample size reduces variability in the data, leading to a smaller error term and a more accurate estimation of the true population parameters. 19) The F-ratio can be made larger A) only by increasing the between-groups mean square. B) only by increasing the within-groups mean square. C) by increasing the within-groups mean square or by decreasing the between-groups mean square. D) by increasing the between-groups mean square or by decreasing the within-groups mean square. Answer: D Rationale: Option D is correct because increasing the between-groups mean square or decreasing the within-groups mean square both contribute to making the F-ratio larger, resulting in a greater likelihood of detecting a significant effect. 20) If the mean square between-groups is the same as the mean square within-groups, then A) the F-ratio will be approximately 1.00. B) the experimental manipulations had large effects. C) the differences between experimental conditions are greater than by chance alone. D) the F-ratio will be very large. Answer: A Rationale: Option A is correct because when the mean square between-groups is equal to the mean square within-groups, it implies that the variability between groups is similar to the variability within groups, resulting in an F-ratio close to 1.00. 21) If there are no systematic differences between the groups, an ANOVA should result in an F-ratio of approximately A) -1.00. B) 2.00. C) +1.00. D) 0.00 Answer: C Rationale: Option C is correct because in the absence of systematic differences between groups, the F-ratio should be close to 1.00, indicating that the variation between groups is similar to the variation within groups. 22) An F value of 1.00 or less in an ANOVA indicates A) a significant difference between groups. B) no significant difference within groups. C) no significant difference between groups. D) a significant difference within groups. Answer: C Rationale: Option C is correct because an F value of 1.00 or less suggests that the observed difference between groups is not statistically significant. 23) An F value of 1.00 or less indicates that there is A) a significant difference between groups. B) no significant difference between groups. C) a large effect due to the experimental manipulation. D) probably a mistake in the computation. Answer: B Rationale: Option B is correct because an F value of 1.00 or less indicates that there is no statistically significant difference between groups. 24) A comparison that is planned before any data are collected is called A) an a priori comparison. B) an a posteriori comparison. C) a post hoc comparison. D) an ad hoc comparison. Answer: A Rationale: Option A is correct because an a priori comparison refers to planned comparisons made before data collection begins, helping to minimize the risk of Type I errors and ensuring the integrity of the research design. 25) The scientific and informational value is generally A) greater for a posteriori than for a priori comparisons. B) greater for a priori than for post hoc comparisons. C) greater for a posteriori than for post hoc comparisons. D) the same for a priori, post hoc, and a posteriori comparison. Answer: B Rationale: A priori comparisons are planned in advance based on theoretical reasoning, which enhances their scientific and informational value compared to post hoc comparisons, which are conducted after observing the data and are more prone to Type I errors. 26) In an ANOVA, an a posteriori comparison A) is a type of planned comparison. B) is made before the planned comparisons are planned. C) is made after a significant F-ratio is found. D) is made only when the planned comparisons reveal significant differences. Answer: C Rationale: A posteriori comparisons are made after a significant F-ratio is found in an ANOVA, typically to determine which specific groups differ significantly from each other after observing the overall significance of the ANOVA. 27) In factorial designs, A) one independent variable is manipulated. B) one dependent variable is manipulated. C) more than one dependent variable is manipulated. D) more than one independent variable is manipulated. Answer: D Rationale: Factorial designs involve the manipulation of more than one independent variable to examine their main effects and interactions. 28) If a design has different participants in each group and the critical comparisons are made between the different groups of participants, the design is considered to be A) a correlated-groups design. B) a within-subjects design. C) an independent-groups design. D) a matched-subjects design. Answer: C Rationale: In an independent-groups design, different participants are assigned to different conditions, and critical comparisons are made between these groups. 29) Research designs in which there are more than one manipulated independent variable are called A) independent-groups designs. B) low-constraint designs. C) correlated-groups designs. D) factorial designs. Answer: D Rationale: Factorial designs involve the manipulation of multiple independent variables to assess their effects on the dependent variable(s). 30) Factorial designs are also called A) multivariable designs. B) univariate designs. C) single-variable designs. D) completely-randomized designs. Answer: A Rationale: Factorial designs are also referred to as multivariable designs because they involve the manipulation of multiple independent variables. 10.5 Ethical Principles 1) What is the best way for researchers deal with the ethical problem raised by randomly assigning some participants to a no-treatment control group? A) by including only a treatment group with no control group B) by not telling participants that they might be in a no-treatment group C) by allowing participants to decide which group they would like to be assigned to D) by obtaining informed consent from participants who are told that they may be assigned to a no-treatment condition Answer: D Rationale: Obtaining informed consent from participants who are aware that they may be assigned to a no-treatment control group addresses the ethical concerns raised by random assignment. 2) What ethical obligation would a researcher studying treatment approaches have to address? A) Both the treatment and control groups should be given the choice of what treatment they want to have. B) If the treatment proves effective, the control group should be given the choice of whether they want the treatment. C) If the treatment proves ineffective, the control group should be given the choice of whether they want the treatment. D) The control group should be given a choice of treatment, but the experimental groups would not get that choice. Answer: B Rationale: Researchers studying treatment approaches have an ethical obligation to offer effective treatments to control groups if the treatment proves effective. 3) When is random assignment to an experimental condition unethical? A) Whenever participants are informed that there will be two conditions. B) Whenever there is more than one experimental condition. C) Whenever there is no difference between the experimental and control conditions. D) Whenever the experimental condition is likely to cause harm. Answer: D Rationale: Random assignment to an experimental condition is unethical when the experimental condition is likely to cause harm to participants. 4) Experimental design emphasizes A) naturalistic approaches. B) control of variance. C) correlational statistics. D) case study approaches. Answer: B Rationale: Experimental design emphasizes the control of variance to ensure that any observed effects are attributable to the manipulated independent variable(s). 5) Random selection helps to A) assign subjects. B) calculate the F-ratio. C) clarify literature searches. D) enhance external validity. Answer: D Rationale: Random selection enhances external validity by increasing the likelihood that the sample is representative of the population from which it is drawn. When participants are randomly selected from a population, it reduces the potential for sampling bias and increases the generalizability of research findings to the broader population. This strengthens the external validity of the study, allowing for more confident extrapolation of results beyond the specific sample studied. Test Bank for Research Methods: A Process of Inquiry Anthony M. Graziano, Michael L. Raulin 9780205900923, 9780205907694, 9780135705056