[R] Specifying starting values in lme (nlme package) using msScale

[Catherine A. Holt]

I am using package nlme and would like to specify initial values for a linear mixed-effects model to help with convergence. I am trying to specify those initial values using the msScale option under ‘control’ in the lme() function:

lme(Y ~ X1,  random= ~ X1|X2, control=list(msScale=lmeScale))

where, (as far as I understand), lmeScale is a function that can take initial values for parameters. However, I am unsure about how to input those starting values (e.g., what names lme will recognize for fixed and random effects, in what format, and if a partial list of initial values would be acceptable?).

Any advice or examples of code inputting starting values would be extremely helpful. I have been unable to find examples myself online. Note, although it may be easier to do this in the lme4 package, I would prefer to use nlme.

Thank you for your attention.
Sincerely, 
Carrie Holt, Ph.D., M.Sc., B.Sc.(Honours)
University of Washington
School of Aquatic & Fishery Sciences
Box 355020
Seattle, WA 98195