An investigation of the effectiveness of a training program to improve customer relationships included a pre-training and a post-training customer survey. to compare the differences, they computed post-training survey score − pre-training survey score. seven customers were randomly selected and completed both surveys. the results are shown here. customer pre-training survey post-training survey a 6 8 b 5 5 c 10 10 d 7 10 e 6 8 f 5 6 g 2 8 this analysis is an example of