Chapter 15, Problem 22P

Although the phenomenon is not well understood, it appears that people born during the winter months are slightly more likely to develop schizophrenia than people born at other times (Bradbury & Miller, 1985). The following hypothetical data represent a sample of 50 individuals diagnosed with schizophrenia and a sample of 100 people with no psychotic diagnosis. Each individual is also classified according to the season in which he or she was born. Do the data indicate a significant relationship between schizophrenia and the season of birth? Test at the .05 level of significance.

	Season of Birth
	Summer	Fall	Winter	Spring
No Disorder	26	24	22	28	100
Schizophrenia	9	11	18	12	50
	35	35	40	40