I am trying to do lme with the library nlme as it is good for ML. If I define the model as:

model<- lme(GHCB~status + age + years_since, random= ~1|Patient/ID, data = cube, na.action = na.omit)



If the model doesn't fit normality, and after assessing all the variables to see which one doesn't have a normal distribution with


I see that none of them is normally distributed. So how should I proceed?

I've tried to log or ^2 the variables but I am not sure how to convert the distribution in a normal distribution, hence, the model is not working.

What do I need to do now? try to convert the variables in "normal" or change the model? and if so, how should I do that?

Thank you very much!! Lili

PS: I attach the qqnorm for the modelenter image description here

  • 1
    $\begingroup$ see robustlmm package for R ... ? also, check for interactions $\endgroup$ – Ben Bolker Jun 23 '18 at 2:01

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