Poindexter finds that r = —.40 between the variables of number of hours studied (X) and number of errors on a statistics test (Y). He also finds that r = + .36 between the variables of time spent taking the statistics test and the number of errors on the test. He concludes that the time spent taking a test forms a stronger relationship with the number of errors than does the amount of study time.
(a) Describe the relative shapes of the two scatterplots.
(b) Describe the relative amount of variability in Y scores at each X in each study.
(c) Describe the relative closeness of Y scores to the regression line in each study.
(d) Is Poindexter correct in his conclusion? If not, what’s his mistake?