David, thanks much--I will check out these resources. Tim
On 2/4/06, David Airey <[email protected]> wrote:
> .
>
> Bill Dupont recently added another .ado to do this (RC_SPLINE). A few
> others are to be found, but I like Bill's. You can use these in
> regression models to flexibly investigate (and test) linear and
> nonlinear relations. See Frank Harrell's text "Regression Modeling
> Strategies" text on the topic. I think you can choose your knot
> placement manually if you have slight gaps, rather than default knots.
>
> > Hello statalisters,
> >
> > A statistics question, not really Stata related:
> >
> > In a recent paper, I used median cubic splines to graphically explore
> > non-linearity in the relationship between two continuous variables.
> > The independent variable, although continuous, was slightly clustered
> > and as a result there were some gaps where no data were available. The
> > reviewer said that because of this, the median cubic spline is not
> > appropriate beacuse it is adapted from time series approaches and
> > requires equidistant data of equal weight for meaningful
> > interpretation. I did not find this prerequisite for this approach in
> > any of my references, or in the Stata documentation. Has anyone else
> > encountered this issue? Is the median cubic spline transformation only
> > appropriate when responses are equidistant?
> > Thanks for any insights, Tim
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