20260224 - GAM interaction

Author: isaactpetersen

regression.qmd

@@ -368,6 +368,7 @@ summary(model2)$adj.r.squared - summary(model1)$adj.r.squared
 When testing for the possibility of moderation/interaction, it is first important to think about what shape the interaction might take.
 If you expect a bilinear interaction (i.e., the slope of the regression line between `X` and `Y` changes as a *linear* function of a third variable, `Z`), it is appropriate to treat the moderator as continuous in moderated multiple regression.
 However, if you expect that the interaction might take a different form (e.g., a threshold effect), you may need to consider other approaches, such as using categorical variables, polynomial interactions, spline functions, generalized additive models (GAMs), or machine learning.
+For info on how to examine an interaction with a GAM, see [Simonsohn (2024)](https://doi.org/10.1177/25152459231207787).
 
 For information on the (low) power to detect interactions and how to improve it, see:
 <https://isaactpetersen.github.io/Principles-Psychological-Assessment/reliability.html#sec-productTerm-reliability>