Refer to Exercise 12.6. The researcher has decided that a more meaningful evaluation of the new program would use the difference between the score on the exam at the end of the fifth grade and that at the end of the fourth grade. Let S4 be the score on the exam at the end of the fourth grade and S5 be the score on the exam at the end of the fifth grade. Initially, the following model was fit to the data set with D = S5 €“ S4.

It was suggested to the researcher that an improved model would express the fifth- grade score, S5, as a function of the fourth- grade score, S4:

a. Rewrite model 1 to express S5 as a function of P, E, G, P * E, P * G, E * G, and S4.
b. Explain why model 2 is a more appropriate model than model 1. Hint: Consider your answer to part (a).

Transcribed Image Text:

Model 1: D = B, + B,P + B,E + B,G + B,PE + BP*G + B,EG +e