Interaction In Stata. The simple effect or slope of x for a one unit change in x the predicted change in y at w 0. Y b 0 b 1 x b 2 w b 3 x w.
An interaction contrast allows you to apply contrast coefficients to both of the terms in a two way interaction. I am not an expert on factor variables. Interactions are formed by the product of any two variables.
The categorical variable is female a zero one variable with females coded as one therefore male is the reference group.
Each coefficient is interpreted as. We will use an example from the hsbdemo dataset that has a statistically significant categorical by continuous interaction to illustrate one possible explanatory approach. We could choose to omit the first level of both a and b the a1 and b1 columns of x and the columns corresponding to a b that match up with those selections in this case the. The categorical variable is female a zero one variable with females coded as one therefore male is the reference group.
