BOUNDS Statement
BOUNDS bound1 <, bound2 ...> ;

The BOUNDS statement imposes simple boundary constraints on the parameter estimates. BOUNDS statement constraints refer to the parameters estimated by the TCOUNTREG 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 >=. Parameter names are as shown in the ESTIMATE column of the “Parameter Estimates” table or can be seen in the OUTEST= data set.

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;

Note: This procedure is experimental.