# Hypothesis Testing & Cohen's d

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Problem Set 1: Chapter 10: problems 2, 14, 22, 24; Chapter 11, problems 2, 4, 12, 20

Chapter 10

2. Describe what is measured by the estimated standard error in the bottom of the independent measures t test.

14. Do you view a chocolate bar as delicious or as fattening...?

Males Females

n = 6 n = 9

M = 31 M = 45

SS = 490 SS = 680

a. Based on these results, is there a significant difference between the attitudes for males and for females? Use a two-tailed test with ? = .05.

b. Compute r2, the percentage of variance accounted for by the gender differences to measure effect size for this study.

22. Steven Schmidt (1994)...Use a two-tailed test with ? = .05

Humorous Sentences Nonhumorous Sentences

4 5 2 4 6 3 5 3

6 7 6 6 3 4 2 6

2 5 4 3 4 3 4 4

3 3 5 3 5 2 6 4

Do the results indicate a significant difference in the recall of humorous versus non-humorous sentences? Use a two-tailed test with alpha = .05.

24. A researcher conducts an independent measures research study and obtains t = 2.070 with df = 28.

a. How many individuals participated in the entire study?

b. Using a two-tailed test with a = .05, is there a significant difference between the two treatment conditions.

c. Compute r2 to measure the percentage of variance accounted for by the treatment effect.

Chapter 11

2. Participants enter a research study with unique characteristics that produce different scores from one person to another. For an independent-measures study, these individual differences can cause problems. Briefly explain how these problems are eliminated or reduced with a repeated-measures study.

4. A researcher conducts an experiment comparing two treatment conditions and obtains data with 10 scores for each treatment condition.

a. If the researcher used an independent-measures design, how many subjects participated in the experiment?

b. If the researcher used a repeated-measures design, how many subjects participated in the experiment?

c. If the researcher used a match-subjects design, how many subjects participated in the experiment?

12. The stimulant Ritalin has been shown to increase attention span and improve academic performance in children with ADHD...n = 25, MD = 6.8, s = 5.5.

a. Is this result sufficient to conclude that Ritalin has a significant effect on attention span? Use a two-tailed test with ? = .01.

b. Compute r2 and an estimated Cohen's d to measure the size of the effect.

20. A researcher uses a matched samples design to investigate whether single people who own pets are generally happier than singles without pets. Test with ? = .05, two-tailed.

Matched Pair Participants from US Pet Owner

A 10 15

B 9 9

C 11 10

D 11 19

E 5 17

F 9 15

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##### Solution Summary

The solution provides step by step method for the calculation of testing of hypothesis. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.

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