Random effects

Random effects are

• the thing that turns a simple linear model (LM) into a linear mixed model (LMM), or a generalised linear model (GLM) into a generalised linear mixed model (GLMM).
• a way the model adjusts the average fixed effect parameters to model different relationships within each level of the grouping variable(s).
• an umbrella term that covers both random intercepts and random slopes.
  • Random intercepts are adjustments to the fixed intercept for each level of the grouping variable.
  • Random slopes are adjustments to the fixed slope for each level of the grouping variable.

In the example lmer() structure below, the random effects appear in the + (1 + ... | g) bit:

CautionTODO Shrinkage

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CautionTODO Pooling

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Linked flash cards

Outgoing links

• TODO

Backlinks

• TODO