eng TQMP Tutorials in Quantitative Methods for Psychology 1913-4126 2012-02-20 8 1 1 22 10.20982/tqmp.08.1.p001 article Howell, Glen T. ghowell_@hotmail.com 1 Lacroix, Guy L. guy_lacroix@carleton.ca 1 Carleton University In this tutorial, we provide researchers who use SPSS step-by-step instructions for decomposing interactions when a three-way ANOVA is conducted using the GLM procedure. We start with a demonstration of how a two-way interaction can be decomposed using the COMPARE subcommand in combination with syntax. Then, we provide instructions with examples for conducting simple interaction and second-order simple effects analyses for three-way ANOVAs with between-subjects, within-subjects, and mixed between- and within-subjects variables using the LMATRIX or MMATRIX subcommands. Provided in Appendices are general rules that can be used to derive design-specific LMATRIX and MMATRIX subcommands. https://www.tqmp.org/RegularArticles/vol08-1/p001/p001.pdf ANOVA interactions GLM SPSS SPSS