Can people really recognize their favorite brand of cola? Volunteers tasted Coca-Cola Classic, Pepsi, Diet Coke, and Diet Pepsi, with results shown below.
Research problem: At α = .05, is correctness of the prediction different for the two kinds of cola drinkers?
Could you recognize your favorite brand in this kind of test?
Since it is a 2 × 2 table, try as well a two-tailed two-sample z test for π1 = π2 and verify that z2 is the same as your chi-square statistic. Which test do you prefer? Why?
Correct |
Regular Cola |
Diet Cola |
Row total |
Yes, got it right |
7 |
7 |
14 |
No, got it wrong |
12 |
20 |
32 |
column total |
19 |
27 |
46 |