A student is interested in whether students who study with music playing devote as much attention to their studies as do students who study under quiet conditions (he believes that studying under quiet conditions leads to better attention). He randomly assigns participants to either the music or no-music condition and has them read and study the same passage of information for the same amount of time. Participants are then all given the same 10-item test on the material. Their scores appear next. Scores on the test represent interval-ratio data and are normally distributed.
The researcher conduct the same study (above) using a within-participants design to control for differences in cognitive ability. He selects a random sample of participants 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 before, 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 Ha 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.