๐”– Bobbio Scriptorium
โœฆ   LIBER   โœฆ

HETEROGENEITY, EXCESS ZEROS, AND THE STRUCTURE OF COUNT DATA MODELS

โœ Scribed by JOHN MULLAHY

Publisher
John Wiley and Sons
Year
1997
Tongue
English
Weight
209 KB
Volume
12
Category
Article
ISSN
0883-7252

No coin nor oath required. For personal study only.

โœฆ Synopsis

This paper demonstrates that the unobserved heterogeneity commonly assumed to be the source of overdispersion in count data models has predictable implications for the probability structure of such mixture models. In particular, the common observation of excess zeros is a strict implication of unobserved heterogeneity. This result has important implications for using count model estimates for predicting certain interesting parameters. Test statistics to detect such heterogeneity-related departures from the null model are proposed and applied in a health-care utilization example, suggesting that a null Poisson model should be rejected in favour of a mixed alternative.

๐Ÿ“œ SIMILAR VOLUMES

13C- and 57Fe-NMR studies of the FeCO un
13C- and 57Fe-NMR studies of the FeCO unit of heme proteins and synthetic model compounds in solution: Comparison with IR vibrational frequencies and X-ray structural data
โœ Charalampos G. Kalodimos; Ioannis P. Gerothanassis; Geoffrey E. Hawkes ๐Ÿ“‚ Article ๐Ÿ“… 1998 ๐Ÿ› John Wiley and Sons ๐ŸŒ English โš– 281 KB ๐Ÿ‘ 2 views

13C- and 57Fe-NMR spectra of several carbon monoxide hemoprotein models with varying polar and steric effects of the distal organic superstructure, constraints of the proximal side, and solvent polarity are reported. The 13C shieldings of heme models cover a 4.0 ppm range that is extended to 7.0 ppm