What are main and interaction effects in statistics?

Can you explain what main and interaction effects are in statistics?

Sure! Main effects refer to the direct impact of an independent variable on a dependent variable. Interaction effects occur when the effect of one independent variable on the dependent variable changes depending on the level of another independent variable.

Can you give me an example of each?

Of course! For main effects, if we study how study hours affect test scores, the main effect is the direct relationship between hours studied and scores. For interaction effects, if we consider both study hours and teaching methods, the effect of study hours on scores might differ depending on the teaching method used.

How do you test for interaction effects?

You can test for interaction effects using ANOVA or regression analysis. In these analyses, you include an interaction term that represents the product of the independent variables.

What are some common mistakes when interpreting these effects?

Common mistakes include assuming that main effects are always significant without considering interactions, or misinterpreting the nature of the interaction itself.