Question

Beer and Diapers: There is a popular story (among data miners) that there is a correlation between men buying diapers and buying beer while shopping. A student tests this theory by surveying 160 male shoppers as they left a grocery store. The results are summarized in the contingency table below.

Observed Frequencies: O_i's

	Bought	Did Not
	Diapers	Buy Diapers	Totals
Beer	8	21	29
No Beer	10	121	131
Totals	18	142	160

The Test: Test for a dependent relationship between buying beer and buying diapers. Conduct this test at the 0.01 significance level.

(a) What is the test statistic? Round your answer to 3 decimal places.

χ²

=

(b) What is the conclusion regarding the null hypothesis?

reject H₀fail to reject H₀    

(c) Choose the appropriate concluding statement.

The evidence suggests that all men who buy diapers also buy beer.The evidence suggests that the probability of a man buying beer is dependent upon whether or not he buys diapers.     There is not enough evidence to conclude that the probability of a man buying beer is dependent upon whether or not he buys diapers.We have proven that buying beer and buying diapers are independent variables.

Answer 1