Re: uninformative groups in 0/1 data
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Re: uninformative groups in 0/1 data




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> Date: Mon, 05 Mar 2001 22:27:56 +1100
> To: asreml@chiswick.anprod.csiro.au
> From: Kim Bunter <kbunter@metz.une.edu.au>
> Subject: uninformative groups in 0/1 data
> Mime-Version: 1.0
> 
> Hi Arthur (and all),
> 
> could you indicate how ASREML deals with uninformative groups for 0/1
> traits? 
ASREML does not do anything automatically other than trying to
estimate an effect on the boundary by limiting the magnnitude
of the fitted value.  There is probably a better approach but I
have not become aware of it.

> Can uninformative groups accidentally "become informative"
> numerically through the fitting of covariates (for example), 
 NO they cannot be made informative unless the GROUP term is not fitted
 (as a fixed effect)
> or are these
> groups removed before any other effects in the model are considered?
If they are casusing problems (which is likely), the user should
drop them.

> 
> Also, are there any tricks to running bivariate analyses with one binary
> and one continuous trait? It seems trait order is important (ie 0/1 trait
> must be specified first). 
  INDEED
>Can either !log or !prob be used, 
   YES
>   and does
> convergence usually need to be helped along with fixing some parameters
> (for example)?
>       
Make sure the problem is not obverspecified and you have good
starting values.  Whether fixing values will help will depend
more on the complexity of the model.

 
> Any comments much appreciated.
> 
> Cheers
> 
> Kim
> Kim Bunter
> Research Scientist
> Animal Genetics and Breeding Unit
> University of New England
> Armidale, NSW, 2351
> AUSTRALIA
> 
> Ph (ISD): -61-2-67733788
> Fax (ISD): -61-2-67733266
> email: kbunter@metz.une.edu.au
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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
Forest Rd, ORANGE, 2800, AUSTRALIA                  home: <61> 2 6362 0046
                                                   Cargo: <61> 2 6364 3288
Until July 2001, I will be mainly building a house at Cargo.

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