All subjects hear music under each of the three methods, the order of presentation being counterbalanced. There are 4 subjects in each group. A covariate is also measured. An Analysis of Covariance is computed and a significant effect of conditions is obtained. An experiment investigates the effect of a drug on the ability to concentrate.
Every subject is tested before and after treatment on a test of focused attention.
Half the subjects are given a drug and the other half are given a placebo. The placebo control group increases its mean score from 6 to 7 while the experimental group increases its mean score from 5 to 6. Explain how it is possible for women to get paid more than men in every department in a company and at the same time for men to have the higher mean salary when computed for the whole company. Discuss the relative advantages and disadvantages of the various methods for testing effects in these designs. For the following data, predict Y from X. Compute Pearson's r, the correlation between predicted and observed, the correlation between residuals and observed.