A market research study was conducted to compare three diffe

A market research study was conducted to compare three different brands of antiperspirant. The results of the study are summarized below. Use a 5% level of significance and test the claim that opinion is independent of brand. Use these data to answer questions 12 and 13. Brand Opinion A B C Total Excellent 29 37 50 116 Satisfactory 83 65 83 231 Unsatisfactory 18 9 6 33 Total 130 111 139 380 What is the value of the sample test statistic?

Solution

expected: contingency table

A B C

1 39.7 33.9 42.4
2 79.0 67.5 84.5
3 11.3 9.64 12.1



chi-square = 11.9
degrees of freedom = 4
probability = 0.018
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What is the value of the sample test statistic?
Answer: X2 = 11.91