The GENSELECT Procedure

PROC GENSELECT Statement

  • PROC GENSELECT <options>;

The PROC GENSELECT statement invokes the procedure. Table 7.1 summarizes the available options in the PROC GENSELECT statement by function. They are then described fully in alphabetical order.

Table 7.1: PROC GENSELECT Statement Options

Option

Description

Basic Options

ALPHA=

Specifies a global significance level

DATA=

Specifies the CAS input data table

MAXOPTBATCH=

Specifies the maximum number of observations to be computed in each batch

Options Related to Output

CORRB

Displays the "Parameter Estimates Correlation Matrix" table

COVB

Displays the "Parameter Estimates Covariance Matrix" table

ITHIST

Displays the "Iteration History" table

NOCHECK

Disables checking for infinite parameters

NOCLPRINT

Limits or suppresses the display of classification variable levels

NOSTDERR

Suppresses computation of the covariance matrix and standard errors

PARTFIT

Displays the fit statistics that are produced when your data are partitioned

STB

Displays standardized estimates

Options Related to Optimization

ABSCONV=

Tunes the absolute function convergence criterion

ABSFCONV=

Tunes the absolute function difference convergence criterion

ABSGCONV=

Tunes the absolute gradient convergence criterion

ABSXCONV=

Tunes the absolute parameter convergence criterion

FCONV=

Tunes the relative function difference convergence criterion

FCONV2=

Tunes the second relative function difference convergence criterion

GCONV=

Tunes the relative gradient convergence criterion

GCONV2=

Tunes the second relative gradient convergence criterion

XCONV=

Tunes the relative gradient convergence criterion

MAXFUNC=

Specifies the maximum number of function evaluations in any optimization

MAXITER=

Chooses the maximum number of iterations in any optimization

MAXTIME=

Specifies the upper limit of CPU time (in seconds) for any optimization

MINITER=

Specifies the minimum number of iterations in any optimization

NORMALIZE=

Specifies whether the objective function is normalized during optimization

TECHNIQUE=

Selects the optimization technique

LASSO Options

LASSORHO=

Specifies the base regularization parameter for the LASSO method

LASSOSTEPS=

Specifies the maximum number of steps for the LASSO method

LASSOTOL=

Specifies the convergence criterion for the LASSO method


The optimization options are fully described in the section Optimization Options in Chapter 3: Shared Concepts. The following list describes the other options available in the PROC GENSELECT statement:

ALPHA=number

specifies a global significance level for the construction of confidence intervals. The confidence level is 1 – number. The value of number must be between 0 and 1. You can override this global significance level by specifying this option in the OUTPUT statement. By default, ALPHA=0.05.

PAGESIZE=number | AUTO
MAXOPTBATCH=number | AUTO

specifies the maximum number of observations to be included in a batch. During the optimization, the GENSELECT procedure reads at most number observations from the data table into memory, performs the appropriate log-likelihood, gradient, and Hessian computations on that batch of observations, then discards those observations and reads in the next batch of data for processing. Generally, a smaller PAGESIZE value decreases memory usage but might lead to longer computation times, whereas a larger PAGESIZE value might lead to shorter computation times but increases memory usage. The default PAGESIZE=AUTO option determines if the entire data table can be held in a subset of your available memory; if not, then it sets PAGESIZE=256.

CORRB

creates the "Parameter Estimates Correlation Matrix" table. The correlation matrix is computed by normalizing the covariance matrix . That is, if is an element of , then the corresponding element of the correlation matrix is , where .

COVB

creates the "Parameter Estimates Covariance Matrix" table. The covariance matrix is computed as the inverse of the negative of the matrix of second derivatives of the log-likelihood function with respect to the model parameters (the Hessian matrix).

DATA=CAS-libref.data-table

names the input data table for PROC GENSELECT to use. The default is the most recently created data table. CAS-libref.data-table is a two-level name, where

CAS-libref

refers to a collection of information that is defined in the LIBNAME statement and includes the caslib, which includes a path to the data, and a session identifier, which defaults to the active session but which can be explicitly defined in the LIBNAME statement. For more information about CAS-libref, see the section Using CAS Sessions and CAS Engine Librefs.

data-table

specifies the name of the input data table.

ITHIST

generates the "Iteration History" table.

LASSORHO=r

specifies the base regularization parameter for the LASSO model selection method. The regularization parameter for step i is r. By default, LASSORHO=0.8.

LASSOSTEPS=n

specifies the maximum number of steps for LASSO model selection. By default, LASSOSTEPS=20.

LASSOTOL=r

specifies the convergence tolerance for the optimization algorithm that solves for the LASSO parameter estimates at each step of LASSO model selection. By default, LASSOTOL=1E–6.

NOCHECK

disables the checking process that determines whether maximum likelihood estimates of the regression parameters exist. For more information, see the section Existence of Maximum Likelihood Estimates.

NOCLPRINT<=number>

suppresses the display of the "Class Level Information" table if you do not specify number. If you specify number, the values of the classification variables are displayed for only those variables whose number of levels is less than number. Specifying number helps to reduce the size of the "Class Level Information" table if some classification variables have a large number of levels.

NOSTDERR

suppresses computation of the covariance matrix and the standard errors of the regression coefficients. When the model contains many variables (thousands), the inversion of the Hessian matrix to derive the covariance matrix and the standard errors of the regression coefficients can be time-consuming. The CORRB, COVB, and TYPE3 options are not available when the NOSTDERR option is specified. This option also disables the quasi-complete separation check; for more information, see the section Existence of Maximum Likelihood Estimates.

PARTFIT

displays fit statistics in the "Fit Statistics" table that are usually produced when your data are partitioned. This option is not required when you specify a PARTITION statement. The statistic that is added to the table is the average square error (or Brier score).

STB

displays the standardized estimates of the parameters in the "Parameter Estimates" table. The standardized estimate of is given by , where is the total sample standard deviation for the ith explanatory variable and

The sample standard deviations for parameters that are associated with CLASS variables are computed using their codings. The standardized estimates are not computed for the intercept parameters.

Last updated: December 21, 2018