[R] Comparing variance components

[Wen Huang]

Dear R-help members,

Say I have two data sets collected at different times with the same design. I fit a mixed model using in R using lmer

lmer(y ~ (1|A))

to these data sets and get two estimates of sigma2_A and sigma2_e

What would be a good way to compare sigma2_A and sigma2_e for these two data sets and obtain a P value for the hypothesis that sigma2_A1 = sigma2_A2? There is obvious shrinkage on these estimates, should I be worried about the differential levels of shrinkage on these estimates and how to account for that?

Thank you for your thoughts and inputs!



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