In Exercise 7 of the regular (not Computer) exercises in the previous chapter, you were asked to calculate the Wilcoxon matched-pairs test to determine whether a training method improved exam scores for 12 poorly performing students. For this exercise, compute the Spearman correlation between the pre- and posttest scores, and test for significance at the .05 level. How does the magnitude of the Spearman correlation relate to the power of the Wilcoxon test?

Data from previous chapter?exercise

A psychology instructor develops a training method that is designed to improve the examination scores of poor students. The performance of a sample of 12 such students on the posttest (X₁) following training, and the pretest (X₂) prior to training, is shown.

Test the null hypothesis that the training method has no effect, using the Wilcoxon test.

1 |77||68 2 ||64||64 3 ||56||52 4 ||56||57 5 ||71||69 6 54||58 7 ||76||70 8 ||57||60 9 ||63||61 10||68||61 11|71||73 12|66||66