Question: #15.28: Can people really identify their favorite brand of cola? Volunteers tasted Coca-Cola Classic, Pepsi, Diet Coke, and Diet Pepsi, with the results shown below. Research question: At α = .05, is the correctness of the prediction different for the two types of cola drinkers? Could you identify your favorite brand in this kind of test? Since it is a 2 x 2 table, try also a two-tailed two-sample z test for ?1 = ?2 and verify that z squared is the same as your chi-square statistic. Which test do you prefer? Why?