19. A study of bulimia among college women (J. Kern and T. Hastings, Journal of Clini- cal Psychology, Vol. 51, 1995. p. 499) considered the effect of childhood sexual abuse on vanous components of a Fanuly Environment Scale. For a measure of family cole- sion. the sample mean for the bulimic students was 2.0 for 13 sexually abused students (s = 21) and 4.8 for 17 nonabused students (s = 3.2)

a) Use small-sample methods to construct a 95% confidence interval for the difference in mean family cohesion for sexually abused students and nonabused students. Interpret What assumptions have you made?

b) Find the P-value for testing whether the population means are equal, against a two- sided altemative. Interpret