A hierarchical model for the analysis of local census undercount in Italy

Census counts are known to be inexact based on comparisons of Census and Post Enumeration Survey (PES) figures. In Italy, the role of municipal administrations is crucial for both Census and PES field operations. In this paper we analyze the impact of municipality on Italian Census undercount rates by modeling data from the PES as well as from other sources using Poisson regression trees and hierarchical Poisson models. The Poisson regression trees cluster municipalities into homogeneous groups. The hierarchical Poisson models can be considered as tools for Small Area estimation.