help for rxrmaxl STB-28: sg45 ------------------------------------------------------------------------------
Generalized ridge regression: shrinkage extent ----------------------------------------------
rxrmaxl depvar varlist [if exp] [in range]
[, msteps(#) omdmin(#) qshape(#) rescale(#) tol(#) ]
To reset problem-size limits, see help matsize.
Description -----------
rxrmaxl calculates three normal-theory, maximum-likelihood criteria (classical, empirical Bayes, and random coefficients) for a choice of shrinkage extent in the ridge regression of depvar on varlist.
Options -------
msteps(#) specifies the number of steps per unit increase in MCAL, the multi- collinearity allowance parameter; the default value is 4. The total numbe > r of steps along the generalized shrinkage path from the least squares solu- tion (MCAL=0) to all zero coefficients (MCAL=p) will thus be 1+(msteps*p).
omdmin(#) is the strictly positive minimum value to be used for calculation of (1-delta) shrinkage factors. The default is 10e-13.
qshape(#) controls the shape (or curvature) of the generalized shrinkage path through likelihood space; the default value is 0, which yields Hoerl- Kennard "ordinary" ridge regression. qshape=1 yields uniform shrinkage, and all qshape values between -5 and 5 are allowed.
rescale(#) controls the scaling of the response variable and all p predictor variables in the varlist. The default value is rescale=1 to scale all centered variables to have sample variance 1. rescale=0 should be specified to retain the original scalings.
tol(#) specifies search convergence criterion and defaults to 0.01.
Example -------
. rxrmaxl mpg cylnds cubins hpower weight, q(-1)
Author ------
Robert L. Obenchain Eli Lilly and Company
Also see --------
STB: STB-28 sg45 On-line: help for rxridge and rxrcrlq