Re: singularities appeared in AI matrix

From: Arthur <asremlforum_at_VSNI.CO.UK>
Date: Fri, 11 Sep 2009 09:07:03 +0100

Dear Ineke,

Brian's comments are right.

Under a sire model, it is possible for the intraclass correlation to exceed 0.25 implying a heritability greater than 1. When that happens, ASReml would fail
to fit an animal model because h2 > 1 implies residual variance is negative.

This can happen if there are fixed effects confounded with sire effects,
and for some data structures, when there are maternal effects and/or
family effects. Since your data is a four level discrete scale, this could be contributing to the problem as well.

Arthur Gilmour

Retired Principal Research Scientist (Biometrics)

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Received on Sat Sep 11 2009 - 09:07:03 EST

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