COUNTREG Procedure

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

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.

For more information about how parameters are named in the BOUNDS statement, see the section Parameter Naming Conventions for the RESTRICT, TEST, BOUNDS, and INIT 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. See also the section RESTRICT Statement.

The following BOUNDS statement constrains the estimates of the parameter for z to be negative, the parameters for x1 through x10 to be between zero and one, and the parameter for x1 in the zero-inflation model to be less than one:

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.