[Fwd: asreml]

From: Alastair Wilson <Alastair.Wilson_at_ED.AC.UK>
Date: Mon, 5 Feb 2007 09:59:43 +0000


I'm fitting a model with an animal effect and a permanent environment
effect. Individuals are spread over two time periods and I want to
test whether a model with time specific animal and PE effects is
better than a model where both periods are treated equally. For
univariate models this is fine:

T1 ~ mu time !r at(time,1).animal at(time,2).animal at(time,
1).identity at(time,2).identity


T1 ~ mu time !r animal identity

If I fit a multivariate model either the animal or the PE effects are
flagged as singular depending on which order the terms are fitted. I
am confident that these parameters can be estimated from the data
because a) all (3) traits have the same pattern of missing data so if
the univariate model is idenitifiable the multivariate model should
be and b) I can fit a multivariate model for each time period
separately by generating two data sets and all model parameters are
estimated. One potential issue is that some individuals are present
in both time periods, but I can't see why this should cause

Any help would be appreciated.

Alastair J Wilson
NERC Research Fellow
tel. 0131 6513673
Institute of Evolutionary Biology
School of Biological Sciences
The University of Edinburgh
Ashworth Laboratories
The King's Buildings
West Mains Road
Edinburgh EH9 3JT, UK
Received on Fri Feb 05 2007 - 09:59:43 EST

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