A researcher would like to evaluate the effectiveness of a pain-relief patch designed for lower back pain. Prior to testing the patch, each ofn= 8 patients rates the current level of back pain on a scale from 1 to 10. After wearing the patch for 90 minutes, a second pain rating is recorded. The data are as follows:

BeforeAfter

62

83

94

81

102

53

98

77

Compute the mean and variance for the sample of difference scores.

Do the results indicate a significant difference?

Use a two-tailed test with=.05

Compute Cohen's d to measure the size of the effect.

What is the Mean Difference for this study?