An investigation of the effectiveness of a training program toimprove customer relationships included a pre-training andpost-training customer survey, 12 customers were randomly selectedto score the customer relationships both before and after thetraining. The differences of scores are calculated as thepost-training survey score minus the pre-training survey score. Thesample mean difference of scores is 0.5. The test statistic is 1.03for testing whether the population mean difference µD ≤ 0.
11. Based on the above information, the sample standarddeviation of the differences of scores is .
A. 1.49
B. 1.53
C. 1.48
D. 1.68
12. Suppose that we want to test whether the training programimproved the customer relationships, the null hypothesis is µD ≤ 0.Which of the following is correct?
A. At the 0.05 significance level, we reject the null, thetraining program improved customer relationships.
B. At the 0.05 significance level, we do not reject the null,the training program did not improve customer relationships.
C. At the 0.10 significance level, we do not reject the null,the training program did not improve customer relationships.
D. At the 0.10 significance level, we reject the null becausethe test statistic is greater than the critical value 1.645.
