A marketing consultant was hired to visit a random sample of five sporting goods stores across the state of California. Each store was part of a large franchise of sporting goods stores. The consultant taught the managers of each store better ways to advertise and display their goods. The net sales for 1 month before and 1 month after the consultant's visit were recorded as follows for each store (in thousands of dollars):
Store 1 2 3 4 5
Before visit 57.3 94.4 49.2 77.4 43.2
After visit 63.7 101.4 57.8 81.2 41.9
Do the data indicate that the average net sales improved? Use = 0.05. (Let d = before − after.)
What are we testing in this problem?
paired difference
difference of proportions
single mean
difference of means
single proportion