Some computational descriptions of moderation analysis

Abstract

Moderation analysis is getting more and more popular as a statistical analysis in psychology and in other social sciences. However, there are very few detailed accounts of the computations performed within the model. Articles are more often focusing on explaining moderation conceptually rather than mathematically. Thus, the purpose of the current paper is to introduce the computation within moderation analysis accompanied with examples with R. Firstly, three moderation models will be described: a continuous variable with another continuous variable, two groups and then three groups. Then, two ways to analyze moderation (regression and analysis of variance) are presented. We will show examples using R and the code to implement all computations presented is offered for the readers to implement it themselves as well as a script to carry a complete example.

Keywords

• moderation analysis
• linear model
• data modelling
• r