Question

1. In an influenza outbreak, you learn that in a factory 13 of 52 men workers were ill. 25 of 52 women workers were ill. Using a hand-calculated chi-square test, determine whether the difference between men and women in illness attack rate is significant. Show your work and answer here.

Answer 1

let us consider the null and alternative hypothesis is

Ho:the difference between men and women in illness attack rate is not significant

Ha: the difference between men and women in illness attack rate is significant

Chi-Square Test
Observed Frequencies(O)
	Attack rate			Calculations
Gender	ill	not ill	Total		fo-fe
Men	13	39	52		-6	6
Women	25	27	52		6	-6
Total	38	66	104
Expected Frequencies€
	Attack rate
Gender	ill	not ill	Total		(fo-fe)2/fe
Men	= = 19	= =33	52		1.894737	1.090909
Women	=19	=33	52		1.894737	1.090909
Total	38	66	104
Data
Level of Significance	0.05
Number of Rows	2
Number of Columns	2
Degrees of Freedom	1
Results
Critical Value	3.841459
Chi-Square Test Statistic	5.971292
p-Value	0.014541
Reject the null hypothesis

Since p value is 0.0145 which is less than 0.05 so we reject Ho and conclude that the difference between men and women in illness attack rate is significant