Using Poisson data

Dear ASREMLers

I have recently used !POIS to estimate variances of poisson distributed
data from a half-sib design. The dire and dam within sire components are
significantly greater than zero but appear impossibly small relative to the
within groups variance. I gather this is an issue to do with the scaling of
poisson variances, and it seems from searching back through the ASREML
discussions that there is no appropriate way to use these variance
estimates to calculate heritabilities.

Likewise, I gather that there is no way to estimate covariances where one
or more traits follows a poisson distribution.

Am I right about these points or am I missing something?

Further, would it be appropriate to use the sire breeding values for each
trait given in the .sln file to estimate the correlation among breeding
values as a rough estimate of the genetic correlation?

Your thoughts on these issues would be much appreciated.

Rob

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School of Biological, Earth and Environmental Sciences
The University of New South Wales
Kensington, Sydney 2052
NSW, Australia

http://www.bees.unsw.edu.au/research/groups/brookslab/brookslab.html
Received on Wed Apr 28 2005 - 10:41:32 EST