CNTSELECT Procedure

The BOUNDS statement imposes simple boundary constraints on the parameter estimates. You can specify any number of BOUNDS statements.

Each bound is composed of parameter names, constants, and inequality operators as follows:

Each item is a constant, a parameter name, or a list of parameter names. Each operator is <, >, <=, or >=. Parameter names are as shown in the Parameter column of the "Parameter Estimates" table. If a parameter name contains a blank or some other special character (such as ’*’, ’-’,’(’, or ’)’), then you must use the internal name of the parameter in order to refer to that parameter in the BOUNDS statement. You can specify the PRINTINTERNALNAMES option in the PROC CNTSELECT statement if you want to see the internal names of the parameters. When you specify the PRINTINTERNALNAMES option, an extra column is added to the "Parameter Estimates" table, which shows the internal name of each parameter.

For more information about how parameters are named, see the section Parameter Naming Conventions for the RESTRICT, TEST, BOUNDS, INIT, and PRIOR Statements.

You can use both the BOUNDS statement and the RESTRICT statement to impose boundary constraints. However, the BOUNDS statement provides a simpler syntax for specifying these kinds of constraints. For more information, see the section RESTRICT Statement.

The following BOUNDS statement illustrates the use of parameter lists to specify boundary constraints. It constrains the estimates of the parameter for z to be negative, the parameters for x1 through x10 to be between 0 and 1, and the parameter for x1 in the zero-inflation model to be less than 1.

bounds z < 0,
       0 < x1-x10 < 1,
       Inf_x1 < 1;

The BOUNDS statement is not supported if a BAYES statement is also specified. In Bayesian analysis, the restrictions on parameters are usually introduced through the prior distribution.