Random intercepts vs random slopes — the difference.
hardAnswer
- Random intercept: each cluster has its own baseline level around the global .
- Random slope: each cluster's slope for a predictor varies around the global β.
- Test which you need with LRT or AIC.
- Rule: if the effect of X differs meaningfully across clusters (users respond differently to price changes), use random slopes.
- Random slopes typically require more clusters (~30+) to fit reliably.
Check yourself — multiple choice
- Same thing
- Random intercept: cluster-specific baseline; random slope: cluster-specific slope on X → tests which via LRT / AIC; slopes need ~30+ clusters
- Only fixed
- Random
Random intercept: baseline varies; random slope: slope varies per cluster.
#mixed-effects#regression
Practise Statistics Fundamentals
215 interview questions in this topic.
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