From: A comparison of statistical methods for modeling count data with an application to hospital length of stay
Sample Size
Poisson
NB
ZIP
ZINB
50
0.6201
0.6158
0.6202
200
0.3039
0.3055
0.3045
600
0.1727
0.1764
0.1736
1000
0.1401
0.1420
0.1402