Question: A high school English teacher measured the attitudes of 11th-grade students toward poetry. After a 9-week unit on poetry, she measured the students' attitudes again. She was disappointed to find that the mean change was zero.
Following are some representative scores. (High scores represent more favorable attitudes.) Calculate s^ for both before and after scores, and write a conclusion based on the standard deviations.
Before 7 5 3 5 5 4 5 6
After 9 8 2 1 8 9 1 2