Basic Statistics

ANSWERS TO SELECTED PROBLEMS 241

much better. The correlation is a measure of the linear association between two

variables.

12.7 (a) Originally, r = -3642 and b = -.8570. With an outlier in Y. T = -.7517

and b = -.8676. With an outlier in X, r = -.8706 and b = -.8237. With an

outlier in both X and Y.r = -.4818 and b = -.5115. (d) The outlier in X

and Y had by far the greater effect. The outlier in Y reduced r but changed b

hardly at all in this example.

Chapter 13

13.1 If the binomial test is used, P < .003, and if the t test is used, P = .004.

13.2 If the normal approximation is used, t = 2.56, so P = .0108. For the exact

test, P < .0031.

13.3 If the normal approximation is used, z = 2.02 and P = .0424 for a two-sided

test.

13.4 The Wilcoxon rank sum test for two independent samples,

13.5 z = 3.14, so P = .0017 for a two-sided test.

13.6 Spearman’s rho for the data in Table 12.2 is .81 and the correlation is 357.

Chapter 14

14.1 No answer.

14.2 Yes, the fit is quite good considering the small sample size.

14.3 The estimated median is .867.

14.4 Too small.

14.5 No answer.