Re: Linear vs curvy splines

From n.holford@auckland.ac.nz Thu Sep 26 14:17:46 1996 Subject: Re: Linear vs curvy splines > > It *is* possible to use plines in $DES. > I have some coding for this as part of my lecture notes > in my Advanced PK course, and if I find the time, I will > try to make this available. We look forward to this... > > But, this is not necessary, as I wrote to Sam yesterday. > A linear spline is adequate to represent Cp. A linear spline *may* be adequate to represent Cp. I personally prefer the idea of a spline with some curvature to it so that I can have a guess at the peak Cp that might be higher than anything I actually measured. The linear interpolation is fine if you have plenty of points. What seemed to be attractive about using CLS is that it was curvy and had other constraints appropriate for describing a pharmacokinetic function which would help when Cp data was relatively sparse. When info is sparse I think one should use any prior info to assist. In this case I am pretty sure that a curvy spline is going to be better than a linear spline. -- Nick Holford, Dept Pharmacology & Clinical Pharmacology University of Auckland, Private Bag 92019, Auckland, New Zealand email:n.holford@auckland.ac.nz tel:+64(9)373-7599x6730 fax:373-7556 http://www.phm.auckland.ac.nz/Staff/NHolford/nholford.html