Question

Suppose a friend of yours thinks that Coke, Diet Coke, and Coke Zero all have the same refreshing taste, but you strongly disagree and think that people prefer (regular) Coke. The two of you do a blind taste-test (after quarantine, of course!) to test the hypothesis that people prefer (regular) Coke over the other two choices. In your study, 15 out of 30 people preferred (regular) Coke. (a) [2 pts] Identify and describe the parameter of interest. (b) [4 pts] State the null and alternative hypotheses, using correct notation, for this hypothesis test. (c) [2 pts] State the value of the sample statistic, and identify it with its correct symbol. (d) [3 pts] Suppose the p-value of the hypothesis test was 0.0345. State, in no uncertain terms, your conclusion at a significance level of 0.05 in the context of the original problem.  It is not enough to say “reject the null” or “fail to reject the null.”  You should not say “such and such is likely” or “such and such probably isn’t true.” What does the sample evidence suggest (or fail to suggest?) about the population? Use language that a non-statistical person could understand.

Answer 1

a)
p1 = proportion of people who prefer Coke

b)
Ho : p1 = p2= p3
Ha : p1 > p2 or p1 > p3

d)
p-value = 0.0345 < alpha (0.05)
hence we reject the null hypothesis
we conclude that it is likely that people prefer (regular) Coke over the other two choices