The BOUNDS statement imposes simple boundary constraints on the parameter estimates. BOUNDS statement constraints refer to the parameters that are estimated by the COUNTREG procedure. You can specify any number of BOUNDS statements as follows.
Each bound is composed of parameter names, constants, and inequality operators as follows:
item operator item < operator item operator item …>
Each item is a constant, a parameter name, or a list of parameter names. Each operator is <, >, <=, or >=.
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.