The verticle line on the top graph represents the mean pre-test score which is 18.6. After we use each pre-test score to subtract the mean value, the bottom figure shows the relationship between the post-test score and the (pre-test score - mean pre-test score).

Question:

After the transformation that subtracted the mean pre-test score from each observation, what happened to the relationship between the pre-test and post-test scores?

Options:

The relationship is identical.

The relationship is weaker.

The relationship is stronger.

40 - 30 O post 20 - O 10- 0 0 25 50 pre40 - 30 - post 20 - 10 - 0 -20 0 20 40 I(pre - mean(pre))