SAS FAQ: When using PROC TRANSREG, what are the defaults with spline?
Proc transreg performs transformation regression in which both the outcome and predictor(s) can be transformed and splines can be fit. Splines are piecewise polynomials that can be used to estimate relationships that are difficult to fit with a single function. In this page, we will walk through an example proc transreg with the spline option and explore its defaults. The bspline, spline, and pspline options, when similarly specified, yield the same results. Their differences lie in the number and type of transformed variables generated for estimation. For more information on the other options available, see the SAS Online Documentation. We can begin by creating a dataset with an outcome Y and a predictor X. This example data is generated in the SAS examples for proc transreg. data a; x=-0.000001; do i=0 to 199; if mod(i,50)=0 then do; c=((x/2)-5)**2; if i=150 then c=c+5; y=c; end; x=x+0.1; y=y-sin(x-c); output; end; run; proc gplot data = a; plot y*x; run; Clearly, there is not a sing
