1. Does a low r necessarily mean that there is little "association" between two variables? (Explain.)
2. It is common to find that the correlation between aviation aptitude test scores (X) and pilot proficiency (Y) is higher among aviation cadets than among experienced pilots. How would you explain this?
3. Some studies have found a strong negative correlation between how much parents help their children with homework (X) and student achievement (Y). That is, children who receive more parental help on their homework tend to have lower achievement than kids who receive little or no parental help. Discuss the possible explanations for why these two variables would correlate negatively. Although one cannot infer causality from a correlation, which explanation do you find most persuasive?
4. Consider the situation where there is absolutely 16. no variability in Y.
(a) What would be the standard deviation of Y?
(b) What would be the covariance between X and Y?
(c) What would be the Pearson r? (Don't respond reflexively!)