does the relationship between x2 and x1 be significant which type of interaction model does x1*x2 represent? what is the main effect of a linear interaction what is the difference between the main impact of an interaction and an interaction without the main effect is there a product term for an interaction which interaction model does not use the product term what is the main effect of x1 in a linear model what is the significance of a general linear model without the main effect? why not include main effects in general linear model what is the purpose of the main effect in a linear model? what is the difference between the main effects and the product term how do i assess the significance of the interaction in an interaction model? which sps model leaves out main effects what is a general linear interaction and what are the main effect why do i leave out the main effects in the linear interaction model? which spss model is not significant when there is the product term? why are the main effects in linear interactions in SPSS? when do i include the main effect of the general linear model why is it important to include product term in a linear model? why do you leave out the main effect in the general linear model?