7.2. Testing for The Difference Between Two Proportions

Often, you want to analyze differences between two populations in the number of nonconforming or defective occurrences. The sample statistics needed to analyze these differences are the proportion of occurrences in population 1 and the proportion of occurrences in population 2. With a sufficient sample size in each group, the sampling distribution of the difference between the two proportions approximately follows a normal distribution.

Table 7.2 summarizes some findings from a study that was conducted at a resort hotel. Management of the hotel had a business objective of increasing the return rate of guests at the hotel. Management decided to focus on the critical first impressions of ...

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