Peter,

As far as I remember, you just have 1 variable, year, on your RHS. So pspline or bspline really doesn't make too much difference. If I were you, I will use pspline.

another consideration is to specifiy the degree freedom explicitly. you can approximate the spline by piecewise linear (which means df = 1) or piecewise constant (which means df = 0).

HTH.

On 9/29/06, Peter Flom <Flom@ndri.org> wrote: > >>> "Wensui Liu" <liuwensui@gmail.com> 9/28/2006 4:05 pm >>> wrote > <<< > I think you are getting what you asked for. > for 11 cases, you want to fit a b-spline with nknot = 3 (which means 4 > basis) and degree = 3 (which is default in SAS). So what do you > expect? > >>> > > What I would like is something so that I can recreate the cubic > equations that apply between each pair of knots, and the location of the > knots. > > SAS Tech Support suggested that this requires use of bspline instead of > spline, but the output from that, while more like what I wanted, is > still not transparent (although I have not yet studied it in detail). > > Peter > > >

-- WenSui Liu (http://spaces.msn.com/statcompute/blog) Senior Decision Support Analyst Cincinnati Children Hospital Medical Center