Suppose that you have collected data throughout a semester from a large elementary school regarding the average number of days per week each math teacher spends in a collaborative teaching community. The average ranges from 0 to 7 days per week. You have also obtained the pre-test and post-test scores in math administered in those same classrooms in the beginning and end of the semester, and you have calculated a score that shows learning during the semester by subtracting the pre-test score from the post-test score for each student.

You are interested in examining any potential relationship between the average number of days of teacher collaborative activities and student learning (i.e., post-test minus pre-test). How can you best handle the data so that you can perform group comparisons to examine the relationship between the two variables? Why is this technique the best for handling the data?