title: Interpretation of interactions: guide for the perplexed.
abstract: In this issue, Zammit et al explore how five dichotomised risk factors work together to predict risk for non-affective psychosis in a large Swedish cohort. In this editorial, we review these findings, and comment on both the nature of additive v. multiplicative models and the meaning of statistical interactions.
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Kendler
authors.forename: Charles O
authors.initials: CO
authors.lastname: Gardner
mesh_terms: D003627:Data Interpretation, Statistical; D006801:Humans; D015233:Models, Statistical; D011618:Psychotic Disorders / Q000453:epidemiology*; D012307:Risk Factors