Free on-line graphing programs for statistical mediation and moderation

Categories: Tools and Resources

Hi everyone!

I’m writing this post to spread the word that I have two free on-line programs to graph mediation and moderation results. They are named MedGraph (for mediation, obviously) and ModGraph (for moderation, even more obviouslier). They can be found on my home page at Victoria University of Wellington (in New Zealand) at:

The way they work is this: 1) compute your regressions in SPSS, Systat, HLM, or other statistical program, and then 2) enter certain values into the on-line menus which will then generate figures depicting your results. I created these applications because SPSS and other programs don’t have very flexible or facile ways to depict mediation or moderation results. If you do either of these techniques, you should find these easy and useful. In addition, you may wish to read the associated Help Centre if you are a beginner to these two techniques. It includes clear exposition about how to do the regressions and enter the desired values into MedGraph or ModGraph.

One last feature: you are able to download an Excel macro for each that will allow you to perform these functions on those occasions when you’re not hooked up to the internet (e.g., sunning on the beach). The ModGraph macro, in particular, is useful because you can customise your obtained figure in the macro whereas the figures generated by the on-line programs are frozen figures (i.e., you can’t modify them).

I hope that some of you will find your way to my programs and avail yourselves of them. There is considerable misunderstanding of these two techniques out there, and I hope that these resources will shed some light on them. Write if you have questions, problems, criticisms, or kudos.