I'm currently writing the results part of my thesis and i'm extremely bad at statistics. My variables are Dependent variable: Responstime (with two levels) Factor: manipulation variable (exposing to either one screen or another screen). Covariate: 7 point scale.

When checking assumptions i found an interaction between the covariate and the independent/factor, resulting in violating of the homogenity of the slopes. My teacher said that i have to use the manipulation variable as a categorical variable and the covariate as a "continues variable" in a multivariate regression analysis in the general linear model (GLM; full factorial). She gave my other fellow students a syntax but forgot me.

Is there somebody who knows have i can get the covariate to be a continues variable and how to conduct a GML (so not an ANOVA)?

Thanks in advance!