A consultation about lmer

Dear anonymous,

The assumption of normality is on the residuals, not on the observations.
The assumption holds reasonably for the sleepstudy, except for a few
outliers.

library(lme4)
fm1 <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy)
qqnorm(residuals(fm1))

Best regards,

ir. Thierry Onkelinx
Statisticus / Statistician

Vlaamse Overheid / Government of Flanders
INSTITUUT VOOR NATUUR- EN BOSONDERZOEK / RESEARCH INSTITUTE FOR NATURE AND
FOREST
Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance
thierry.onkelinx at inbo.be
Havenlaan 88 bus 73, 1000 Brussel
www.inbo.be

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Op ma 23 dec. 2019 om 17:36 schreef ??? <18754808835 at 163.com>:

 I have some confusion about the use of lmer. As I learned the data
should  be normal distributed when use liner mixed model. I tested the
exmple  data (Reaction$sleepstudy) by using shapiro.test. The result shows
that  it was not normal distributed.  So I have some confusion about the
requirment of data distribution in function lmer and glmmer.
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