I have 3 columns of data, a nominal LABEL identifies which of 3 populations the row is from, a continuous DURATION is the independent variable, and a continuous EFFECT is the dependent variable. Using Analyze>Fit Y by X from the menu I can get 3 regression lines with ANOVA for each, but I want an ANCOVA comparing the slopes of the 3 lines. According to JMP help: "In the Fit Least Squares report, the Compare Slopes option appears when there is one nominal term, one continuous term, and their interaction effect for the fixed effects. This option produces a report that enables you to compare the slopes in an analysis of covariance (ANCOVA) model." but I can't find this option...