There are some things you need to understand about TRANSREG. I designed it for linear models with nonlinear (sometimes iteratively derived) transformations. However, I later made it do other things that seemed important that no one else was doing. Hence, I added BOXCOX. Univariate BOXCOX was even more of a stretch, but someone needed to do it, so I made it work (albeit with a somewhat clunky specification). Similar to BOXCOX, I added smoothing splines even though they did not fit well with the rest of the procedure. Decades ago, the old sasware ballot had getting the smoothing splines from GPLOT into an output data set. I knew GPLOT would never do it, so I put it in TRANSREG. The documentation has lots of details that can help you understand what it does. In some ways it is like a Swiss Army knife—lots of functionality but not always maximally elegant for a specific tool.
... View more
