MODEL dependent-variable = regressors </ options> ;
The MODEL statement specifies the dependent variable and independent regressor variables for the regression model. The dependent
count variable should take only nonnegative integer values from the input data set. PROC HPCOUNTREG rounds any positive noninteger
count value to the nearest integer. PROC HPCOUNTREG discards any observation that has a negative count.
Only one MODEL statement can be specified. You can specify the following options in the MODEL statement after a slash (/).
-
DIST=value
-
specifies a type of model to be analyzed. You can specify the following values:
- POISSON | P
-
specifies the Poisson regression model.
- NEGBIN(P=1)
-
specifies the negative binomial regression model that uses a linear variance function.
- NEGBIN(P=2) | NEGBIN
-
specifies the negative binomial regression model that uses a quadratic variance function.
- ZIPOISSON | ZIP
-
specifies zero-inflated Poisson regression.
- ZINEGBIN | ZINB
-
specifies zero-inflated negative binomial regression.
You can also specify the DIST option in the HPCOUNTREG statement.
-
NOINT
-
suppresses the intercept parameter.
-
OFFSET=offset-variable
-
specifies a variable in the input data set to be used as an offset variable. The offset-variable is used to allow the observational units to vary across observations. For example, when the number of shipping accidents
could be measured across different time periods or the number of students who participate in an activity could be reported
across different class sizes, the observational units need to be adjusted to a common denominator by using the offset variable.
The offset variable appears as a covariate in the model with its parameter restricted to 1. The offset variable cannot be
the response variable, the zero-inflation offset variable (if any), or any of the explanatory variables. The “Model Fit Summary” table gives the name of the data set variable that is used as the offset variable; it is labeled “Offset.”
You can specify the following options in either the PROC HPCOUNTREG statement or the MODEL statement:
-
CORRB
-
prints the correlation matrix of the parameter estimates.
-
COVB
-
prints the covariance matrix of the parameter estimates.
-
NOPRINT
-
suppresses all printed output.
-
PRINTALL
-
requests all printing options.
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