I am currently using the simple slope analysis to examine the significant interaction effects between my continuous moderator and a dichotomous predictor (values 1 & 2)on a continuous DV. I have 2 continuous covariates in the analysis.
My simple slope graph however showed negative values in the DV (i.e: moderator values at predictor value 2 accounted for negative amounts of DV - the slopes crossed the x-axis towards the bottom right direction). Is this possible, or is there some statistical error? I have seen slopes going into the negative values of DV for continuous predictors, but not for dichotomous predictors.