Question

A study by Bradbury and Miller (1985) recorded the birthdate and schizophrenia diagnosis (schizophrenia vs no schizophrenia). Birthdates were categorized into seasons (summer, fall, winter, and spring). The table below contains the frequencies of 150 birthdates and diagnoses and row and column totals. Use a chi-square test for independence.  

	Summer	Fall	Winter	Spring	Total
No Schizophrenia	26	24	22	28	100
Schizophrenia	9	11	18	12	50
Total	35	35	40	40	N = 150

a) State the null and alternative hypotheses.

b) State the alpha level.

c) Calculate the expected frequencies, the chi-square statistic, and the p-value.  

d) Decide to reject or fail to reject the null hypothesis and interpret that decision.  

e) Calculate the phi squared $LaTeX: \phi^2$ ?2 effect size.

Answer 1