In SPSS there are user-written programs to help model mediation effects.
- For the simplest model in which there is only one mediator, one independent variable and one outcome variable, all of which are continuous variables, you can use the program below.
This program estimates the percentage of the total effect that is mediated and the ratio of the indirect to the direct effect by using the Sobel test, written by William Dudley PhD and Jose Benuzillo MA, University of Utah College of Nursing, 2/11/04. We thank the authors of this program very kindly for sharing it with us and for allowing us to post it on our site.
You can download a word document explaining their program here .
- For more complicated models, you can use the program given on the page here.