Once interaction has been established between $x _ { 1 }$ and $x _ { 2 }$, the first-order terms for $x _ { 1 }$ and $x _ { 2 }$ may be deleted from the regression model leaving the higher-order term containing the product of $x _ { 1 }$ and $x _ { 2 }$.

Question

Quizplus · Accepted Answer

In regression models, even if an interaction term is included, the first-order terms for the interacting variables should generally be retained to properly interpret the interaction effect.

Once Interaction Has Been Established Between x1x _ { 1 }x1​

Once Interaction Has Been Established Between $x _ { 1 }$