Chapter 10 Experimental Design and Analysis II
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1.Using the same subjects in each condition in an experiment is to using different subjects in each condition in an experiment as _____ is to _____.a. / between-subjects design; within-subjects design
b. / control group; experimental group
c. / within-subjects design; between-subjects design
d. / experimental group; control group
ANSWER: / c
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—THINK CRITICALLY
2.A design in which the same participants are used in each condition is a _____ design.
a. / matched-subjects
b. / between-subjects
c. / within-subjects
d. / across-subjects
ANSWER: / c
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—UNDERSTAND
3.A design in which the participants in the experimental and control groups are related in some way is a _____ design.
a. / correlated-groups
b. / between-subjects
c. / across-subjects
d. / none of the options is correct
ANSWER: / a
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—UNDERSTAND
4.A problem for within-subjects designs in which the order of the conditions has an effect on the dependent variable is
a. / counterbalancing.
b. / order effects.
c. / a Latin square effect.
d. / the individual differences effect.
ANSWER: / b
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—UNDERSTAND
5.A mechanism for controlling order effects either by including all orders or treatment presentations or by randomly determining the order for each participants is
a. / ordering.
b. / counterbalancing.
c. / a Latin square.
d. / counterbalancing and a Latin square.
ANSWER: / d
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—UNDERSTAND
6.When we use different subjects in each condition, but they are related on some variable or variables, we are using a _____ design.
a. / matched-subjects
b. / between-subjects
c. / within-subjects
d. / across-subjects
ANSWER: / a
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—UNDERSTAND
7._____ are more of a concern for _____-subject designs, but tend not to be as great a concern for _____-subject designs.
a. / Order effects; within; between
b. / Order effects; between; within
c. / Demand characteristics; between; within
d. / none of the options is correct
ANSWER: / a
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—THINK CRITICALLY
8.Which of the following is a type of correlated-groups designs?
a. / within-subjects designs
b. / matched-subjects designs
c. / between-subjects designs
d. / both within-subjects designs and matched-subjects designs
ANSWER: / d
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—UNDERSTAND
9.Concerns for within-subjects designs frequently include _____ and _____.
a. / order effects; nonequivalent control groups
b. / carryover effects; mortality
c. / carryover effects; order effects
d. / all of the options are correct
ANSWER: / c
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—THINK CRITICALLY
10._____ is a strength of matched-subjects designs but a weakness of between-subjects designs.
a. / Equivalency of groups
b. / Minimized testing effects
c. / Minimized demand characteristics
d. / none of the above
ANSWER: / a
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—THINK CRITICALLY
11.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—APPLY
12.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
13.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
14.tcv = 3.35 and tobt = -3.55. Based on these results, we
a. / reject Ho.
b. / fail to reject Ho.
c. / accept Ho.
d. / reject Ha.
ANSWER: / a
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—THINK CRITICALLY
15.For a correlated-groups t test, the null hypothesis states that
a. / H0: m1-m2 = 0.
b. / H0: m1-m2 > 0.
c. / Ha: m1-m2 = 0.
d. / Ha: m1-m2 > 0.
ANSWER: / a
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
16.For a correlated-groups t test, the alternative hypothesis states that
a. / H0: m1-m2 = 0.
b. / H0: m1-m2 > 0.
c. / Ha: m1-m2 = 0.
d. / Ha: m1-m2 > 0.
ANSWER: / d
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
17.If a correlated-groups t test and an independent-groups t test both have df=16, which experiment used more participants?
a. / They both used the same number of participants (n=18).
b. / They both used the same number of participants (n=17).
c. / The correlated-groups t test used more participants.
d. / The independent-groups t test used more participants.
ANSWER: / d
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
18.In a research study comparing two conditions, researchers obtain 24 scores from each condition. If this was a within-subjects design, then there were _____ participants in the study.
a. / 24
b. / 25
c. / 26
d. / 48
ANSWER: / a
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
19.If researchers reported that, for a correlated-groups design, t(20) = 3.57, p<.05, you can conclude that
a. / a total of 21 people participated in the study.
b. / a total of 22 people participated in the study.
c. / a total of 40 people participated in the study.
d. / the number of participants cannot be determined.
ANSWER: / a
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
20.If researchers reported that, for a correlated-groups design, t(20) = 3.57, p<.05, you can conclude that
a. / the null hypothesis should be rejected.
b. / that you should fail to reject the null hypothesis.
c. / the alternative hypothesis was incorrect.
d. / the study needs to be repeated.
ANSWER: / a
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
21.When using a correlated-groups t test, df =
a. / n1 + n2 - 2.
b. / n - 1.
c. / n1 + n2 - 1.
d. / n - 2.
ANSWER: / b
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
22.In a correlated-groups design, if n = 20, then df =
a. / 20.
b. / 19.
c. / 21.
d. / 40.
ANSWER: / b
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
23.Imagine that you conducted a correlated-groups t test with 12 participants. For a two-tailed test, the tcv at α = .05 would be
a. / ±1.796.
b. / ±2.201.
c. / ±1.782.
d. / ±2.179.
ANSWER: / b
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
24.One advantage of the correlated-groups t test over the independent-groups t test is that it reduces the error variance due to
a. / the degrees of freedom.
b. / the independent variable.
c. / the dependent variable.
d. / individual differences.
ANSWER: / d
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
25.Identify the two types of correlated-groups designs discussed in the text and explain why each is considered a correlated-groups design.
ANSWER: / The two types of correlated-groups designs are a within-subjects design and a matched-subjects design. Each is considered a correlated-groups design because there is some relationship between the subjects in each group when using these designs. In the within-subjects design, the same people are used in each condition and in the matched-subjects design, subjects are matched on relevant variables before being placed into each condition.
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—UNDERSTAND
26.Explain what counterbalancing is, how it is achieved, and which confound it helps to minimize.
ANSWER: / Counterbalancing is a mechanism for controlling order effects either by including all orders of treatment presentations or by randomly determining the order for each participant. This controls for order effects, which occur when the order of the conditions has an effect on the dependent variable. Order effects are problematic for within-subjects designs.
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—UNDERSTAND
27.Explain what a Latin square is and how it helps with counterbalancing.
ANSWER: / A Latin square is a counterbalancing technique to control for order effects without using all possible orders. Several orders are selected through construction of the Latin square, and these are the order of conditions used for participants.
KEYWORDS: / TWO-GROUP CORRELATED-GROUPS DESIGNS—UNDERSTAND
28.A researcher believes exercise reduces anxiety in women. She identifies a group of women who had not exercised before, but are now planning to begin exercising. She gives them a 50-item anxiety inventory before they begin exercising and administers it again after 6 months of exercising. The anxiety inventory is measured on an interval scale and higher numbers indicate higher anxiety. In addition, scores on the inventory are normally distributed. The scores appear below.
BeforeAfter
46 44
41 40
42 39
47 46
43 42
45 43
ANSWER: / a) What statistical test should be used to analyze these data?
A correlated-groups t test should be used.
b) Identify H0 and Ha for this study.
H0:m1m2
Ha:m1m2
c) Conduct the appropriate analysis.
t (5) = 5.0, p = .002.
d) Should H0 be rejected? What should the researcher conclude?
Yes, H0 should be rejected. The researcher should conclude that exercise reduces stress
significantly.
e) If significant, compute the effect size and interpret this.
Cohen’s d is 2.03—a very large effect size. We could also use r2, which is .83, also indicating
a very large effect size.
f) If significant, draw a graph representing the data.
g) Calculate the 95% CI.
The 95% CI is -.82 to -.249
KEYWORDS: / PARAMETRIC INFERENTIAL STATISTICS: TWO-GROUP DESIGNS—APPLY
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