IV.29. Unhappy HMO patients. A study of complaints by HMO members compared those who filed complaints about medical treatment and those who filed nonmedical complaints with an SRS of members who did not complain that year. Here are the data on the number who stayed and the number who voluntarily left the HMO:

	No complaint	Medical complaint	Nonmedical complaint
Stayed	721	173	412
Left	22	26	28

(a) Find the row and column totals. (Hint: See pages 572–573.)
(b) Find the percentage of each group who left. (Hint: See pages 572–573.)
(c) Find the expected counts and check that you can safely use the chi-square test. (Hint: See pages 576, 581–582.)
(d) The chi-square statistic for this table is x² = 31.765. What null and alternative hypotheses does this statistic test? What are its degrees of freedom? How significant is it? What do you conclude about the relationship between complaints and leaving the HMO? (Hint: See pages 574–583.)