To measure the effect of a storewide sales campaign on non-sale items, the research director took a random sample of 13 pairs of stores that were matched according to average weekly sales volume. One store of each pair (the experimental group) was exposed to the sales campaign, and the other member of the pair (the control) group was not. The following data indicated sales for the stores over a one week period: (in $1,000s)
Store # With Marketing Campaign Without Marketing Campaign
1 67.2 65.3
2 59.4 54.7
3 80.1 81.3
4 47.6 39.8
5 97.8 92.5
6 38.4 37.9
7 57.3 52.4
8 75.2 69.9
9 94.7 89.0
10 64.3 58.4
11 31.7 33.0
12 49.3 41.7
13 54.0 53.6
Does the sample data provide evidence to conclude that the average sales of non-sale items in the stores receiving campaign is greater than the average sales of non-sale itmes in the stores not receiving the campaign? Use theta=.05
a. Which of the t-test methods are you going to use and why?
b. Formulate the null and alternative hypothesis
c. Determine the criterion for rejection or nonrejection of the null
d. What is the t-statistic for this analysis
e. Compare the test statistic to the rejection region and make a judgment about the null and alternative hypothesis.
f. Interpret the statistical decision in terms of the problem
g. What is the observed p value in this hypothesis test? What does it mean?