The researcher in exercise 5 in Chapter 9 decides to conduct the same study using a within-subjects design to control for differences in cognitive ability. He selects a random sample of subjects and has them study different material of equal difficulty in both the music and no-music conditions. The study is completely counterbalanced to control for order effects. The data appear next. As in Chapter 9, they are measured on an interval-ratio scale and are normally distributed; he believes that studying under quiet conditions will lead to better performance.

Music                                    No Music

7……………………………………………….7

6……………………………………………….8

5……………………………………………….7

6……………………………………………….7

8……………………………………………….9

8……………………………………………….8

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

b. Identify H₀ and H_a for this study.

c. Conduct the appropriate analysis.

d. Should H₀ be rejected? What should the researcher conclude?

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

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

g. Determine the 95% confidence interval.