Two-way ANOVA and what interactions mean.

hard

Answer

$Tests three effects at once: main effect of factor A, main effect of factor B, and A\timesB interaction.$
$Interaction: the effect of A depends on the level of B.$
$Significant interaction means main effects are hard to interpret in isolation (plot cell means to visualize).$
$Assumptions: normality + equal variances + independence within cells.$
$Foundation of factorial experimental design.$

Check yourself — multiple choice

One-effect only
Tests main A + main B + A×B interaction; significant interaction complicates main-effect interpretation
Same as one-way
Only for regression

Two-way ANOVA: main + main + interaction — interaction complicates main effects.

#hypothesis-testing#parametric-tests

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