The COUNTREG procedure is controlled by the following statements:
PROC COUNTREG
options ;
BOUNDS
bound1 < , bound2 …> ;
BY
variables ;
CLASS
variables ;
FREQ
variable ;
INIT
initvalue1 <, initvalue2 …> ;
MODEL
dependent variable = regressors / options ;
NLOPTIONS
options ;
OUTPUT
options ;
RESTRICT
restriction1 <, restriction2 …> ;
WEIGHT
variable ;
ZEROMODEL
dependent variable
zero-inflated regressors / options ;
There can only be one MODEL statement. The ZEROMODEL statement, if used, must appear after the MODEL statement, and the CLASS statement must precede the MODEL statement. If a FREQ or WEIGHT statement is specified more than once, the variable specified in the first instance is used.