Calculating the Pearson's Product-Moment Correlation Coefficient (r)

1. Think about Z scores.
How do you know if you are doing well in a distribution as compared to another distribution? If you have a high Z score on the SATs and it predicts your GPA - you should have a high Z score on the GPAs. You would be in the top of each distribution.

If your GPA stinks, I would expect your SATs to be not so hot. You would be below the mean on both and have negative Z scores.