Problem 1:
You are designing your dissertation. You want to see if humor affects systolic blood pressure (BP). You plan to have one condition where a lecture is presented that includes humorous remarks and humorous pictures in the accompanying PowerPoint that is used in the lecture. You plan to have a second condition where a lecture (on a different topic but of equal interest and difficulty) is presented that includes NO humorous remarks or humorous pictures in the accompanying PowerPoint.
You plan to measure each participant’s BP at the end of the lecture that is presented.
a. How would you assign participants if you plan to use an independent t-test to compare systolic BP after the humorous versus the nonhumorous lecture?
b. How would you assign participants if you plan to use a repeated measures design and the t-test for related samples to compare systolic BPs in the two conditions?
c. How would you assign participants if you plan to use a matched pairs design and the t-test for related samples to compare systolic BPs in the two conditions?
Problem 2:
Why is a difference score used in computing the t-value for a related t-test?
Problem 3:
1. Compute the t-value for a repeated measures design:
Null hypothesis: There is no difference in outcome scores (the DV measure) between condition A and Condition B.
Alternative hypothesis: There is a difference in outcome scores (the DV measure) between condition A and Condition B.
You have set alpha at .05. Based on the t-value you compute, do you accept or reject the null hypothesis?
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Condition A
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Condition B
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S1
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15
|
10
|
|
S2
|
15
|
12
|
|
S3
|
12
|
8
|
|
S4
|
19
|
18
|
|
S5
|
17
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15
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Problem 4:
Compute the effect size, Cohen’s d, for the problem in Question 3. (See p. 361 in textbook, Chap. 11).Interpret the effect size (what does it tell you?).
Problem 5:
What does 95% confidence interval mean? What would it be for the study described in Question 3? Why do we compute it? (See pp. 361-362. This is also discussed in previous chapters).