orthog polynomials and splines
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orthog polynomials and splines


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)?

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?

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 ?

Thanks a lot,


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