>The component for spl(time) is a variance component, but it controls the
>amount of smoothing. If this component (actually the ratio gamma) tends
>to zero, the spline fit tends to a straight line, as it gets large the
>fit tends to interpolation. The additional variance component, ie
>dev(time), allows for the presence of group effects, and can only be
>fitted if there is replication at each (or most) time point. This is in
>line with the usual one-way random effects analysis where you would fit
>y~ mu !r group
>in asreml to get correct analysis ie estimating both an error and between
>groups variance.
>
>The usual roughness penalty that is described in most smoothing texts is
>actually lambda = 1/gamma(spl).
Thank you for your remarks. As you know, it is customary to specify
heritability as a function of the genetic and total variability. In
formulating linear functions of the variance components, should the
components for spl(time) and dev(time) be considered a part of the total
variability or should one include them in the genetic variation?
Peter /
>...........................................................................
....
> Brian Cullis Tel: 02 6938 1855
> NSW Agriculture Fax: 02 6938 1809
> Wagga Agricultural Institute email: brian.cullis@agric.nsw.gov.au
> Pine Gully Rd
> WAGGA WAGGA NSW 2650
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