[R-sig-ME] Residual setting with makeLmer in simR package

[Fan, L.]

Hi all,

I have a doubt about how to set residual sd (sigma) for a PA, using makeLmer function of the simR package.

When defining the fixed effect, my parameter estimates were all standardized coefficients (i.e., I standardised/z-scored all the variables beforehand). When defining the random structures, since I extracted them from another similar but not same-structured study, I also used the standardized variances (variance divided by sum of variances) for random intercepts and slopes to match them with my manipulation for the fixed parts. 

When I tried to fill the sigma of makeLmer function, I got a little bit lost. It is said in the manual that I should enter the sd of the residual. However, since I standardized the random effects, I believe the residual sd should also be different than the original unstandardized one. My question is, how should I deal with this sigma part, should I indeed use a standardized residual sd? And if yes, should it be simply valued as 1, or how should I standardize it?

Thanks!

Best wishes,

Lei Fan