Predictors: triceps skinfold thickness (X1), thigh circumference (X2), midarm circumference (X3). Response: body fat New R code that may be helpful: library (car) vif (mr) where mr is an Im object. We will consider several models: Model 1: E(Y) = 0 + X1 + 2X2 + 3X3 Model 2: E(Y) = 0 + 2X2 + 3X3 Model 3: E(Y) = 0 + 2X2