A researcher is interested in whether listening to music assists or hinders test-performance. To control for differences in cognitive level, this researcher decides to employ a within-participants design. He selects a random sample of participants and has them study different material of equal difficulty in both the music and no music conditions. Participants take a 20-item quiz on the material. The table below shows the scores on the quiz. The study is completely counterbalanced to control for order effects. The scores obtained are measured on an interval-ratio scale and are normally distributed.
Music No Music
17 17
16 18
15 17
16 17
18 19
18 18
a. What statistical test should be used to analyze the data?
A correlated-groups t-test would be appropriate to analyze the data; there are two sets of scores, one for music and one for no music.
b. Is this a one- or two tailed test?
This is a two-tailed test
c. Identify H0 and Ha for this study.
The mean difference between the performance of the candidates = 0
The alternative hypothesis is that the mean difference between the performance of the candidates is not zero
d. Conduct the appropriate analysis. Should H0 be rejected? What should the researcher conclude?
The P - value = 0.041 < ? = 0.05, we reject H0. At the 5% significance level, the mean difference between the performance of the candidate is not zero. The researcher should conclude that listening to music helps to improve test performance.
e. Calculate the 95 confidence interval.