Perilou Goddard (2003) designed a Writing in Psychology course to help college students learn important skills needed for the preparation of formal psychological research reports. Students were administered precourse and postcourse tests on their knowledge of the writing style recommended by the American Psychological Association. Goddard carried out a statistical analysis on the precourse and postcourse means.

1. Which statistical test seems most appropriate for the statistical analyses?

a. t test for one sample

b. t test for two independent samples

c. t test for two related samples

d. t test for a correlation coefficient

e. One-factor F-test

f. Two-factor F-test

g. Repeated-measures F test

h. One-variable χ² test

i. Two-variable χ² test

A paragraph from Goddard’s results section is shown below. Use the information presented in this paragraph to answer questions 2 to 7.

The maximum possible number of correct answers on the APA style tests was 40. The precourse mean score was 20.74 (SD = 3.80); the postcourse mean score improved to 23.85 (SD = 4.23). Again, a two-tailed paired-sample t test revealed a significant difference t(26) = -3.68, p = .001. (p. 28)

2. The standard deviation of the precourse test scores was equal to ___.

3. The standard deviation of the postcourse test scores was equal to ___.

4. The obtained precourse-postcourse difference between the means was equal to ___.

5. Degrees of freedom for the analysis were equal to ___.

6. How many students provided test scores for the analysis?

7. With a significance level of .05, critical t is equal to ___.