Let model 1 be the same model with only an intervention variable, say X3, as in question 7. Let model 2 be the same model with the addition of variables age and body mass index , i.e, with X3 as the intervention variable (0,1). Let the prediction equation be:
Model 1: ^Y=bo + b3 * X3
Model 2: ^Y=bo + b3 * X3 + b4 * Age + b5 * BMI
In general , will b3 be the same in both prediction equations? How does the interpretation of b3 in Model 2 different from the interpretation in Model 1, if at all?