Hi Tapan,

The following line using lme from the nlme package should work:

testRes <- lme(Y ~X1+X2,random=~1|FAM_ID,correlation=corSymm(form = ~1|FAM_ID),data=fam_dat)

testRes <- lme(Y ~X1+X2,random=~1|FAM_ID,correlation=corSymm(),data=fam_dat) should be equal.

I hope this helps. Sometimes I had the problem that the REML did not converge using the corSymm(), whereas using a compound symmetry structure worked.

Best,

Stephan
 



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*Stephan Moratti, PhD/
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