Likelihood

Hi ASRemlers,

Shouldn't log likelihood only increase (significantly or otherwise) when an
effect (fixed or random) is added to a model?
However, I have found it to decrease with the addition of an effect, in
some cases. For example, if a non-significant effect is added or if an
effect confounded with another already present in the model, is added. Is
this happening because ASReml doesn't necessarily find the highest
likelihood every time? Or maybe this is why LogL can be used for a LRT to
test significance of fixed effects using the same random model (Lynch and
Walsh- "Genetics and analysis of quantitative traits", p.860).

Grateful for your comments.

Chanda Nimbkar

Ms. Chanda Nimbkar
Ph.D. student
Animal Science (Room 35, Postgrad Annexe)
School of Rural Science and Agriculture
University of New England
Armidale, NSW 2351
Australia

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Received on Wed Jan 13 2005 - 14:54:05 EST