st: Plotting and testing of interaction effects (continuous variables)

[Roman Wörner <h0953997@wu.ac.at>]

Dear list members,


I am fairly new to STATA and statistics in general - I'm thus very sorry 
in case my questions appear pretty basic to most of you.


As part of my project I regress a performance variable (DV) on two 
explanatory variables, their interaction and a set of controls (IVs). 
Both explanatory variables (the interacted ones) are continuous. To 
allow for a better interpretation of the interaction many papers present 
simple slope graphs of the interactions (basically high/low combinations 
of the two variables) combined with significance tests of the slope of 
the one variable at the two levels of the other.


I found "Cohen et al. (2003): Applied Multiple Regression/Correlation 
Analysis for the Behavioral Sciences" very helpful since they explain 
the math in Chapter 7 "Interactions Among Continuous Variables". So I 
think I should be able to do both the plotting and testing by hand. 
However, I was wondering if there is a (user written) STATA command 
available which could be used to create the plots as well as to do the 
significance tests.

Many thanks

Roman

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