= Interaction
{disambiguate=statistics}
{wiki}
= Statistical interaction
{synonym}
= Interaction
{synonym}
A statistical interaction means that the effect of one predictor depends on another on the chosen response scale. In a <linear regression>, an <interaction term> $\beta_3XZ$ changes the slope in $X$ to $\beta_1+\beta_3Z$. Whether interaction is present depends on the comparison scale; additive effects and multiplicative effects use different null contrasts. Comparing subgroup effects requires an <interaction contrast>, rather than contrasting their separate significance labels.
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