如何从混合模型（lmer）中提取学生化残差？

Question

Here is my model,

MY = lmer(MY ~ Energy*Protein + (1|Sequence/Cow) + (1|Period), data = CH4CO2)

Is there a function that can extract studentized residuals?

Answer 1

Here is what I did according to the definition,

StudentResid = function(fit){
  res = residuals(fit)
  H = hatvalues(fit)
  sigma = summary(fit)$sigm
  sres = sapply(1:length(res), function(i) res[[i]]/(sigma*sqrt(1-H[[i]])))
  test = abs(sres) > 3
  ifelse(any(test), which(test), NA)
}

StudentResid(MY)

Here I return the observations that has a relatively large studentized residual, considering as outlier. Looks good?