>
> Dear ASREMLers,
> Can someone please throw some light on the following ASREML
> prediction:
>
> I have a model predicting variety means using code:
>
> yield ~ mu c(Varname) c(tos) c(Year) c(Newzone),
> !r TrialID
> 1 1 0 !WT=nrep
> 0 0 0
> predict Varname
>
> The predicted variety means are all exactly 62 kgs lower than those from
> GENSTAT.
> However, the raw mean is 2347 (which I presume GENSTAT adjusts to,
> BUT ASREML estimates mu=2421
> So, strangely, the ASREML overall mean is HIGHER???
> than GENSTAT.
>
> Peter Clarke
> --
Dear Peter,
Simple things first: Genstat does not allow you to use
'Sum to Zero' Constaints. It uses 'Corner point' constraints.
It predicts the 4way table Varname x tos x Year x Newzone
and then averages over the cells to produce the Varname table.
Is the 4 way table complete? Genstat has various options for forming means.
when the table is not complete.
ASREML does an equivalent thing but may get different results if
there are holes in the 4way table.
You have used a weighted analysis so this could explain the difference
between the raw mean and mu.
The fixed difference of 62 suggests a difference in the base for
calculation. The mean of the Varname values from ASREML under
your model should be 2421. If not, then it suggests that
the other factors are not being averaged over.
I would need to see the Genstat output and the ASREML output to
comment further.
Arthur
> Asreml mailinglist archive: http://www.chiswick.anprod.csiro.au/lists/asreml
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Arthur Gilmour PhD mailto:Arthur.Gilmour@agric.nsw.gov.au
Principal Research Scientist (Biometrics) fax: <61> 2 6391 3899
NSW Agriculture <61> 2 6391 3922
Orange Agricultural Institute telephone work: <61> 2 6391 3815
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