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*To*: asreml@chiswick.anprod.csiro.au, Kim Bunter <kbunter@metz.une.edu.au>*Subject*: RE: Solutions for FE under link functions*From*: "Janss, L.L.G." <l.l.g.janss@id.dlo.nl>*Date*: Mon, 24 Sep 2001 13:30:52 +0200*Sender*: asreml-owner@lamb.arm.li.csiro.au

Dear Kim: A meaningful interpretation of the solution from the logit model can be obtained by computing EXP(solution or contrast). This gives Relative Risks, also called Odds Ratio's. I agree with Arthur that your solutions from the probit model are way off scale: they should be roughly from -3 to +3 for probit (underlying standard normal distribution) or about -5 to +5 for logistic (underlying logistic distribution). These very high values for solutions for Fixed Effects indicate usually an unidentifiability of some effect or level. Greetings, Luc Janss. > ID-Lelystad > P.O. Box 65 > 8200 AB Lelystad, The Netherlands > > -----Original Message----- > From: Kim Bunter [SMTP:kbunter@metz.une.edu.au] > Sent: Monday, September 24, 2001 2:41 AM > To: asreml@chiswick.anprod.csiro.au > Subject: Solutions for FE under link functions > > Dear Arthur, > > when 0/1 data is analysed with the probit (or logit) link function, do the > solutions for fixed effects have any meaning? For example, the following > solutions are obtained for management groups under either animal (A) or > sire (S) models, when assuming normality (N) or using the probit link > function (P). > > AN SN SP > 0.33 0.33 71.61 > 0.38 0.38 71.80 > 0.43 0.43 71.86 > 0.58 0.59 72.72 > > What is the interpretation of these results, and why are SP values of such > a different magnitude? The differences between solutions for each level > also vary. Are computed F_values informative for modelling purposes when > using the link functions? > > 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 > -- > Asreml mailinglist archive: > http://www.chiswick.anprod.csiro.au/lists/asreml -- Asreml mailinglist archive: http://www.chiswick.anprod.csiro.au/lists/asreml

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