Understanding Moderation Effects and Analysis: Identifying Interactions between Variables , Study notes of Statistics

Download Understanding Moderation Effects and Analysis: Identifying Interactions between Variables and more Study notes Statistics in PDF only on Docsity! 1/9/2009 1 Moderation Effects and Analysis Definition An effect that identifies a qualitative or quantitative variable that affects the direction and/or strength of the relation between two variables _________________________ Answers “Who” and “When” Begin with two variables and their association Ex. Incentives and motivation are positively correlated Although the association is well- established, we might not know FOR WHOM or WHEN this is more likely to be the case (i.e., an “it depends” question) Moderation answers this question 1/9/2009 2 Moderation = _________________________ Just like a 2 X 2 experimental design involves interaction effects, advanced correlational designs can examine how two independent variables interact to influence the outcome In the previous example, we would be looking at an Incentive X Disinterest effect on Motivation _________________________ of Analysis Exactly the same as a Factorial ANOVA Main effects Interaction effect Factorial ANOVAs are actually specialized versions of regression analyses using categorical IVs Difference: You need to create an “interaction term” Steps in Creating the __________________Term Identify which variables are the IV and moderator The variables in the interaction term must include 0 in possible scores, so you will usually have to revise the original scores C t i la egor ca Keep it simple: only use two groups Recode as 0 and 1 Continuous Create a centered variable Centered score = Score – Mean (deviation score) Using these new scores, multiply the two new variables together for each person (using Compute function). The product of these two variables is the Interaction Term