## Research Methods and Statistics A Critical Thinking Approach 5th Edition by Sherri L. Jackson – Test Bank

**Multiple Choice**

1. Independent variable is to dependent variable as _____ is to _____.

a.

measure; manipulate

b.

manipulate; measure

c.

control group; experimental group

d.

experimental group; control group

*ANSWER: *

b

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—THINK CRITICALLY

2. Baseline is to treatment as _____ is to _____.

a.

dependent variable; independent variable

b.

independent variable; dependent variable

c.

control group; experimental group

d.

experimental group; control group

*ANSWER: *

c

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—THINK CRITICALLY

3. In an experimental study of the effects of exercise on stress, stress is the

a.

dependent variable.

b.

independent variable.

c.

control group.

d.

experimental group.

*ANSWER: *

a

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—APPLY

4. In an experimental study of the effects of exercise on stress, exercise is the

a.

dependent variable.

b.

independent variable.

c.

control group.

d.

experimental group

*ANSWER: *

b

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—APPLY

5. In an experimental study of the effects of exercise on stress, subjects are randomly assigned to either the no exercise group or the exercise group. These groups represent the _____ and the _____, respectively.

a.

independent variable; dependent variable

b.

dependent variable; independent variable

c.

control group; experimental group

d.

experimental group; control group

*ANSWER: *

c

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—APPLY

6. To say that an experiment contains a confound means that

a.

different subjects are assigned to each group.

b.

the dependent variable is measured.

c.

the independent variable is manipulated.

d.

there is an uncontrolled extraneous variable in the experiment.

*ANSWER: *

d

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

7. Internal validity is

a.

the extent to which the results of an experiment can be attributed to the manipulation of the dependent variable, rather than to some confounding variable.

b.

the extent to which the results of an experiment can be attributed to the manipulation of the independent variable, rather than to some confounding variable.

c.

the extent to which the results of an experiment can be generalized.

d.

both b and c.

*ANSWER: *

b

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

8. Changes that occur naturally in the subjects over time could result in the confound of

a.

history.

b.

maturation.

c.

regression to the mean.

d.

diffusion of treatment.

*ANSWER: *

b

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

9. John conducted an experiment to test the effectiveness of a smoking cessation program. The experiment took place over a 1-month time period. Participants in the control group and the experimental group (those who participated in the smoking cessation program) recorded the number of cigarettes that they smoked each day. John was unaware that “national stop-smoking week” also happened to take place during the 1-month time period of his experiment. John’s experiment is now confounded by

a.

maturation.

b.

history.

c.

regression to the mean.

d.

mortality.

*ANSWER: *

b

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—APPLY

10. A decline in performance due to repeated testing is a(n) _____ effect and improvement in performance due to repeated testing is a(n) _____ effect.

a.

instrumentation; mortality

b.

mortality; instrumentation

c.

practice; fatigue

d.

fatigue; practice

*ANSWER: *

d

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

11. After grading 20 very poor term papers, Professor Jones was so upset by his students’ writing that he became even more conscious of errors in their papers. Professor Jones’ change in his grading criteria is similar to the confound of

a.

mortality.

b.

history.

c.

instrumentation.

d.

diffusion of treatment.

*ANSWER: *

c

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—APPLY

12. The best advice for those considering retaking the SAT is that if your score was below average you probably ____ retake the test, and if your score was above average you probably ____ retake the test due to _____.

a.

should; should; mortality

b.

should; should not; regression to the mean

c.

should not; should; regression to the mean

d.

should; should not; mortality

*ANSWER: *

b

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—THINK CRITICALLY

13. When subjects are lost differentially from the experimental and control groups, any observed effect may be due to

a.

mortality.

b.

instrumentation.

c.

diffusion of treatment.

d.

history.

*ANSWER: *

a

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

14. After participating in an experiment on the effects of alcohol on sociability, Megan could not wait to return to her sorority house to tell all of her sisters about it. In this situation, the researcher should be concerned with the confound of

a.

mortality.

b.

regression to the mean.

c.

testing.

d.

diffusion of treatment.

*ANSWER: *

d

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—APPLY

15. Single-blind experiments help to control for ____ effects whereas double-blind experiments help to control for _____ effects.

a.

participant; experimenter and participant

b.

experimenter and participant; participant

c.

fatigue; practice

d.

practice; fatigue

*ANSWER: *

a

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

16. A limitation in the ability to differentiate between scores at the bottom of the scale is a _____ and a limitation in the ability to differentiate between scores at the top of the scale is a _____.

a.

practice effect; fatigue effect

b.

fatigue effect; practice effect

c.

ceiling effect; floor effect

d.

floor effect; ceiling effect

*ANSWER: *

d

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

17. Alison’s bathroom scale will not register a weight of more than 130 pounds. Alison does not realize this, and therefore is unaware that she has put on a few pounds until she begins to notice how tight her clothes are. This illustrates the confound of a _____ effect.

a.

ceiling

b.

floor

c.

practice

d.

fatigue

*ANSWER: *

a

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—APPLY

18. When we can generalize from the sample used in a study to the population of interest, we say that the study has _____ validity.

a.

internal

b.

external

c.

construct

d.

content

*ANSWER: *

b

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

19. Increasing the number of levels of the independent variable is to _____ replication as changing the type of dependent measure is to _____ replication.

a.

exact; conceptual

b.

conceptual; exact

c.

systematic; exact

d.

systematic; conceptual

*ANSWER: *

d

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—THINK CRITICALLY

20. Sometimes it is difficult to generalize the results of a study to the population because of the _____ problem.

a.

diffusion of treatment

b.

college sophomore

c.

regression to the mean

d.

mortality

*ANSWER: *

b

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

21. An independent-groups *t* test

a.

compares sample means for two related groups.

b.

compares sample means for two unrelated groups.

c.

compares standard deviations for two unrelated group.

d.

compares sample means for three or more unrelated groups.

*ANSWER: *

b

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—UNDERSTAND

22. As sample variance _____, the value of the *t* test _____.

a.

increases; increases

b.

decreases; decreases

c.

increases; decreases

d.

increases; stays the same

*ANSWER: *

c

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—THINK CRITICALLY

23. If, after calculating an independent-groups *t* test you find that it is equal to zero, then

a.

the two sample means differ significantly.

b.

the two sample means do not differ significantly.

c.

you have done something wrong.

d.

the two population means differ significantly.

*ANSWER: *

b

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—THINK CRITICALLY

24. Which of the following *t* test results has the greatest chance of statistical significance?

a.

*t*(28) = 1.70

b.

*t*(14) = 1.70

c.

*t*(18) = 1.70

d.

*t*(10) = 1.70

*ANSWER: *

a

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—THINK CRITICALLY

25. If the null hypothesis is true, then the *t* test should be close to

a.

0.00.

b.

±1.65.

c.

±1.96.

d.

±3.00.

*ANSWER: *

a

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—THINK CRITICALLY

26. Imagine that you conducted an independent-groups *t* test with 12 participants in each group. For a two-tailed test, the *t*_{cv} at *a* = .05 would be

a.

±1.717.

b.

±2.074.

c.

±1.711.

d.

±2.064.

*ANSWER: *

b

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY

27. If a researcher reported for an independent-groups *t* test that *t*(18) = 2.90, *p*< .01, how many participants were there in the study?

a.

18

b.

20

c.

10

d.

9

*ANSWER: *

b

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—THINK CRITICALLY

28. The null hypothesis for a two-tailed independent-groups *t* test states that

a.

*H*0: *m*1 ¹ *m*2.

b.

*H*0: *m*1 = *m*2.

c.

*H*a: *m*1 ¹ *m*2.

d.

*H*a: *m*1 = *m*2.

*ANSWER: *

b

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—UNDERSTAND

29. The alternative hypothesis for a two-tailed independent-groups *t* test states that

a.

*H*0: *m*1 ¹ *m*2.

b.

*H*0: *m*1 = *m*2.

c.

*H*a: *m*1 ¹ *m*2.

d.

*H*a: *m*1 = *m*2.

*ANSWER: *

c

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—UNDERSTAND

30. If an independent-groups *t* test has seven participants in each group, then the degrees of freedom are

a.

7.

b.

14.

c.

6.

d.

12.

*ANSWER: *

d

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY

31. When using an independent-groups *t* test, the difference between the means is divided by the standard error of the

a.

mean.

b.

standard deviation.

c.

difference between means

d.

difference between standard deviations.

*ANSWER: *

c

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—UNDERSTAND

32. Which of the following are aspects of a study that can increase power?

a.

greater differences produced by the independent variable

b.

smaller variability of raw scores in each condition

c.

increased sample size

d.

all of the options are correct

*ANSWER: *

d

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—THINK CRITICALLY

33. For an independent-groups *t* test, effect size can be measured using

a.

Cohen’s *d*.

b.

the standard error of the difference between means.

c.

the phi coefficient.

d.

the *c*2 test for independence.

*ANSWER: *

a

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—UNDERSTAND

34. Which of the following is not an assumption of the *t* test for independent groups?

a.

The data are interval or ratio.

b.

The underlying distributions are bell-shaped.

c.

The observations are independent.

d.

There is not homogeneity of variance.

*ANSWER: *

d

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—UNDERSTAND

35. For an independent-groups *t* test, the value of Cohen’s *d* describes

a.

the size of the treatment effect.

b.

the chance of a Type I error.

c.

the chance of a Type II error.

d.

the overall chance level in the experiment.

*ANSWER: *

a

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—UNDERSTAND

**Subjective Short Answer**

36. A health magazine recently reported a study in which researchers claimed that iron supplements increased memory and problem-solving abilities in a random sample of college women. All of the women took memory and problem-solving tests at the beginning of the study, then took iron supplements, and then took the same tests again at the end of the study. What is wrong with this design? What confounds could be leading to the results of improved memory and problem-solving skills?

*ANSWER: *

*This is a single-group pretest/posttest design. In other words, there is no control group, and there should be a control group. The problem is that the subjects could have done any number of things between the pretest and posttest (in addition to taking iron supplements) that could have also led to this improvement. Thus, there could be a practice effect or a maturation effect.*

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—APPLY

37. In an experimental study of the effects of exercise on stress, subjects are randomly assigned to either the no exercise or the exercise conditions. Identify what type of study this is—between-, within-, or matched-subjects. In addition, identify the independent and dependent variables and the control and experimental groups.

*ANSWER: *

*This is a between-subjects design. The independent variable is amount of exercise and the dependent variable is stress. The control group would be those who do not exercise and the experimental group is those who do.*

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—APPLY

38. What are the advantages and disadvantages in the use of a posttest-only control group design versus a pretest/posttest control group design?

*ANSWER: *

*With a posttest-only control group design we do not have to worry as much about demand characteristics, experimenter effects, or practice or fatigue effects. However, because we do not use a pretest, we cannot be absolutely sure that the participants are equivalent at the beginning of the study. With the pretest/posttest control group design, we can be sure of equivalency of subjects, however we need to be more concerned about demand characteristics, experimenter effects, and practice and fatigue effects.*

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

39. What is a confound and how is it related to internal validity?

*ANSWER: *

*A confound is an uncontrolled extraneous variable or flaw in an experiment. It is a threat to internal validity because it means that the results of the experiment might not be due to the manipulation of the independent variable, but instead to the confounded variable.*

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

40. Briefly explain the confounds of history and maturation.

*ANSWER: *

*History is a threat to internal validity in which an outside event that is not a part of the manipulation of the experiment could be responsible for the results. Maturation is a threat to internal validity in which naturally occurring changes within the subjects could be responsible for the observed results.*

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

41. Briefly explain the confounds of testing and regression to the mean.

*ANSWER: *

*Testing is a threat to internal validity in which repeated testing leads to better or worse scores (practice or fatigue effects). Regression to the mean is a threat to internal validity in which extreme scores, upon retesting, tend to be less extreme, moving toward the mean.*

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

42. Briefly explain the confounds of instrumentation and mortality.

*ANSWER: *

*Instrumentation is a threat to internal validity in which changes in the dependent variable may be due to changes in the measuring device. Mortality, or attrition, is a threat to internal validity in which differential dropout rates may be observed in the experimental and control groups, leading to inequality between the groups.*

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

43. Briefly explain the relationship between participant effects, experimenter effects, single-blind experiments, and double-blind experiments.

*ANSWER: *

*A participant effect is a threat to internal validity in which the participant, consciously or unconsciously, affects the results of the study. A single- or double-blind experimental procedure can help to control for this. An experimenter effect is a threat to internal validity in which the experimenter, consciously or unconsciously affects the results of the study. Single and double-blind experimental procedures can help control for this also. A single-blind procedure controls for either participant or experimenter effects whereas a double-blind procedure controls for both at the same time.*

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—THINK CRITICALLY

44. What is the relationship between external validity and the college sophomore problem?

*ANSWER: *

*External validity is the extent to which the results of an experiment can be generalized. Because most research in psychology is completed on college sophomores, generalizability (or external validity) can be problematic.*

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—THINK CRITICALLY

45. Differentiate between an exact replication, a systematic replication, and a conceptual replication.

*ANSWER: *

*An exact replication involves repeating a study using the same means of manipulating and measuring the variables as in the original study. A conceptual replication involves designing a study based on another study that uses different methods, a different manipulation, or a different measure. A systematic replication is a study that varies from an original study in one systematic way—for example, by using a different number or type of participants, a different setting, or more levels of the independent variable.*

*KEYWORDS: *

TWO-GROUP BETWEEN-SUBJECTS DESIGNS—UNDERSTAND

46. According to some research, males have better spatial skills than do females; and according to other research, females have better reading skills than males. A student is interested in determining which gender performs better on a word-search puzzle (a puzzle in which words are hidden vertically, horizontally, and diagonally within an array of letters) since this type of puzzle involves both spatial and reading skills. A sample of males and females volunteer to participate and are given 10 minutes to work on a 50-word puzzle. The number of words correctly recognized is recorded for each subject, and the resulting data are as follows:

**Males Females**

12 15

8 12

9 11

11 18

10 13

12 14

__ 7 17 __

Conduct the appropriate analysis of these data and determine whether there are any significant differences.

*ANSWER: *

*An independent samples* t *test should be performed on these data, with* t *(12) = -3.64, p<.01. Yes, there are significant differences between the groups. Females performed significantly better on the task than males.*

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY

47. A college student is interested in whether there is a difference between male and female students in the amount of time spent working out each week. The student gathers information from a random sample of male and female students on her campus. Amount of time spent working out is normally distributed. The data appear below.

__ Males Females__

7 5

5 9

9 8

10 3

6 10

2 5

__ 4 9 __

*ANSWER: *

a) What statistical test should be used to analyze these data?

*The independent samples* t *test.*

b) Identify *H*_{0} and *H*_{a} for this study.

*H*_{0}*:**m1**=**m2
*

*H*

_{a}*:*

*m1*

*¹*

*m2*

c) Conduct the appropriate analysis.

*t (12) = -.58.*

d) Should *H*_{0} be rejected? What should the researcher conclude?

*No,* H_{0}* should not be rejected.*

e) If significant, compute the effect size and interpret this.

*Not necessary*

f) If significant, draw a graph representing the data.

*Not necessary*

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY

48. A student is interested in whether students who study with others devote at much attention to their studies as do students who study alone. He believes those who study alone devote more attention to their studies. He randomly assigns participants to either group or individual study conditions and has them read and study the same passage of information for the same amount of time. Participants are then all given the same 10-item test on the material. Their scores appear below. Scores on the test represent interval/ratio data and are normally distributed.

__Group Alone__

6 10

5 9

6 7

5 7

6 6

6 6

7 8

8 6

__5 9 __

*ANSWER: *

a) What statistical test should be used to analyze these data?

*The independent-groups* t *test.*

b) Identify *H*_{0} and *H*_{a} for this study.

*H*_{0}*:**m1*__<__*m2*

* H*_{a}*:**m1**>**m2*

c) Conduct the appropriate analysis.

*t (16) = -2.60, p<.01.*

d) Should *H*_{0} be rejected? What should the researcher conclude?

*Yes,* H_{0}* should be rejected. The researcher should conclude that when students studied
alone, they did significantly better on the test.*

e) If significant, compute the effect size and interpret this.

*Cohen’s d is 1.22—a large effect size. We could also use* r^{2}*which is .30, indicating
a large effect size.*

f) If significant, draw a graph representing the data.

g) Calculate the 95% CI.

* The 95% CI is -2.832 to -.288*

*KEYWORDS: *

PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY

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