[R] Function for linear mixed model with gamma-distributed random effects?

[Christopher Hatherly]

Hi,
I'm new to R and am hoping someone might be able to help with the following lme problem.
I am trying to fit an ellipse equation to some spatial human factors data, varying the major and minor axes randomly and specifying an exp~ variogram for errors. Using normally-distributed random effects produces some -ve minor/major axes. I am hoping to be able to specify a gamma distribution to overcome this, but have not been able to work out how.
Does anybody know an R function that implements lme with gamma-distributed random effects?
Any help or advice would be greatly appreciated!
Thanks

Chris Hatherly
PhD Candidate
Ageing Research Unit
Centre for Mental Health Research
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christopher.hatherly at anu.edu.au