Question

Do consumers spend more on a trip to Store A or Store​ B? Suppose researchers interested in this question collected a systematic sample for 85 Store A customers and 82 Store B customers by asking customers for their purchase amount as they left the store. Using the given summary​ statistics, researchers calculated a​ 95% confidence interval for the mean difference between Store A and Store B purchase amounts. The interval was ​($negative 15.96​,$negative 4.04​). Explain in context what this interval means.

Answer 1

We can be 95% confident that consumers spend between $4.04 and $15.96 less at Store A than the consumers spend at Store B.

Explanation:

Confidence Intervals give an estimate as range of values for a statistic concerned at a confidence level.

In this case the statistic is the mean difference between Store A and Store B purchase amounts and the confidence level is 95%.

Confidence Interval can be calculated using M±ME where

• M is the sample mean difference between Store A and Store B purchase amounts

• ME is the margin of error from the mean