Data Set Options

DATA=SAS-data-set

specifies the input SAS data set. If the DATA= option is not specified, PROC COUNTREG uses the most recently created SAS data set.

Output Data Set Options

OUTEST=SAS-data-set

writes the parameter estimates to an output data set.

COVOUT

writes the covariance matrix for the parameter estimates to the OUTEST= data set. This option is valid only if the OUTEST= option is specified.

Printing Options

NOPRINT

suppresses all printed output.

Estimation Control Options

COVEST=value

The COVEST= option specifies the type of covariance matrix of the parameter estimates. The quasi-maximum likelihood estimates are computed with COVEST=QML. The default is COVEST=HESSIAN. The supported covariance types are as follows:

OP

specifies the covariance from the outer product matrix.

HESSIAN

specifies the covariance from the Hessian matrix.

QML

specifies the covariance from the outer product and Hessian matrices.

Options to Control the Optimization Process

PROC COUNTREG uses the nonlinear optimization (NLO) subsystem to perform nonlinear optimization tasks. All the NLO options are available. For details, see Chapter 6, Nonlinear Optimization Methods. In addition, the following option is supported on the PROC COUNTREG statement:

METHOD=value

specifies the iterative minimization method to use. The default is METHOD=NRA.

QN

specifies the quasi-Newton method.

NRA

specifies the Newton-Raphson method.

TR

specifies the trust region method.