Compute the simple regression equation for Y on a for b one SD below the mean.

Question

A study has collected data on 50 participants. Predictor variable A has a mean value of 12.0 and SD = 2.0. Predictor variable B has a mean of 7.5 and SD = 1.5. Dependent variable Y is regressed onto the standardised predictors, denoted a and b, yielding the regression equation:

E(Y) = 12.4+2.6a+3.4b−1.3ab
Compute the simple regression equation for Y on a for b one SD below the mean.

1. 9 + 3.9a

2. 7.3 + 4.55a

3. 15.8 + 1.3a

4. 17.5 + 0.65a