Researchers at Harris Interactive wondered if there was a difference between males and females in regard to whether they typically buy name-brand or store-brand products. They asked a random sample of males and females the following question: "For each of the following types of products, please indicate whether you typically buy name-brand products or store-brand products?" Among the 1104 males surveyed, 343 indicated they buy name-brand over-the-counter drugs; among the 1172 females surveyed, 295 indicated they buy name-brand over-the-counter drugs. Does the evidence suggest a lower proportion of females buy name-brand over-the-counter drugs?
(a) Explain why this study can be analyzed using the methods for conducting a hypothesis test regarding two independent proportions.
(b) What are the null and alternative hypotheses?
(c) Describe the sampling distribution of p̅female - p̅male. Draw a normal model with the area representing the P-value shaded for this hypothesis test.
(d) Determine the P-value based on the model from part (c).
(e) Interpret the P-value.
(f) Based on the P-value, what does the sample evidence suggest? That is, what is the conclusion of the hypothesis test? Assume an α = 0.05 level of significance.