Count Data Models

Count data models have a dependent variable that is counts (0, 1, 2, 3, and so on). Most of the data are concentrated on a few small discrete values. Examples include: the number of children a couple has, the number of doctors visits per year a person makes, and the number of trips per month that a person takes.

Handouts, Programs, and Data

Count Data Models

Count Data Models Example

Count Data Models Stata Program and Output

Count Data Models in Stata.do

count_docvisit.dta

Count Data Models R Program and Output

Count Data Models in R.R

count_docvisit.csv

Count Data Models SAS Program and Output

Count Data Models in SAS.sas

count_docvisit.csv

Count data models: topics covered

    • Poisson model (properties of the distribution, coefficients, and marginal effects)

    • Negative binomial model (test for overdispersion and incidence rate ratios)

    • Hurdle or two-part models

    • Zero-inflated models