A Researcher Would Like to Evaluate the Effectiveness of a Pain-Relief

Short Answer

A researcher would like to evaluate the effectiveness of a pain-relief patch designed for lower back pain.Prior to testing the patch,each of n = 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:
$$\begin{array} { r c } \text { Before } & \text { After } \\\hline 6 & 2 \\8 & 3 \\9 & 4 \\8 & 1 \\10 & 2 \\5 & 3 \\9 & 8 \\7 & 7\end{array}$$
a.Compute the mean and variance for the sample of difference scores.
b.Do the results indicate a significant difference? Use a two-tailed test with α = .05
c.Compute Cohen's d to measure the size of the effect.