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*To*: asreml@chiswick.anprod.CSIRO.AU*Subject*: orthog polynomials and splines*From*: Arthur Gilmour <gilmoua@ornsun.agric.nsw.gov.au>*Date*: Tue, 26 May 1998 12:24:23 +1000 (EST)*Reply-To*: Arthur Gilmour <gilmoua@ornsun.agric.nsw.gov.au>*Sender*: owner-asreml

- > Hi, > Three questions related to random regressions: > How are constructed the orthogonal polynomials in ASREML (or what is de family > of polynomials that Arthur used for the program)? The orthogonal polynomial coefficients are print in the .asl file if you use the -DL command line option. I have list track of the source of the subroutine but I think it was given me by Brian Coote over 20 years ago. > If the polynomials are really orthogonal I think the variance matrix of the > > polynomial coefficients should be a diagonal, but checking in the .res file > > after fitting a DIAG matrix shows covariance terms different from 0. However, > if I try to fit a US matrix, the program does not converge (and it is just > > > jumping from one value to other). Should I just assume that they are zero? The coefficients are orthogonal when taken as a single replicate. More likely you have unequal replication of the X values so that across the data file, they will not be orthogonal. If you take as starting values, those from the .res file after fitting DIAG, I would have thought you should be able to get to convergence. I would use !STEP 0.1 if it failed to converge initially.\ COnvergence may be difficult to achieve when there are other random factors in the model which might use some of the variation. > If I include something like subject.spl(age) as part of my model (to use a > > > random regression) how is the G matrix specified for that term? > e.g. y~spl(age) !r subject.spl(age) etc... ... > subject.spl(age) 2 > subject 0 > spl(age) 0 …? I wouldbe looking at adding a few more terms: (I presume spl(age) as a fixed effect is a typo! Try y ~ mu lin(age) !r spl(age) subject subject.age subject.spl(age) dev(age) ... For this model, you do not need to specify a G structure for any terms [but you may want to allow a covariance between slope and intercept subject 2 2 0 US .1 -.01 .1 subject I would build up to this though - first fitting the simpler model so as to get reasonable starting values. Arthur Thanks a lot, Luis &~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~> Luis Apiolaza Palmerston North, New Zealand Web: http://www.geocities.com/Yosemite/Gorge/3063/ Email: cronopio@altavista.net "Quote me as saying I was misquoted" - Groucho Marx &~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~> ------------- End Forwarded Message ------------- <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> Arthur Gilmour PhD email: Arthur.Gilmour@agric.nsw.gov.au Senior 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 ASREML is currently free by anonymous ftp from pub/aar on ftp.res.bbsrc.ac.uk Point your web browser at ftp://ftp.res.bbsrc.ac.uk/pub/aar/ in the IACR-Rothamsted information system http://www.res.bbsrc.ac.uk/ To join the asreml discussion list, send the message subscribe to asreml-request@chiswick.anprod.CSIRO.au The address for messages to the list is asreml@chiswick.anprod.CSIRO.au <> <> <> <> <> <> <> "Seek first the kingdom of God and His righteousness" Jesus; Matthew 6: 33 <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

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