[R] White standard errors for lme?

[Owen Wu]

How can I compute Huber/White standard errors for mixed-effects models?

The function "robcov" in the design library can only provide Huber/White standard errors for models that have a residuals(fit,type=score) function implemented, such as lrm, cph , coxph, and ordinary linear models (ols).  But I hope to do the same for lme (linear mixed-effects models).

Thanks in advance