Heterogeneity and behavioral response in continuous time capture-recapture, with application to street cannabis use in Italy

TL;DR

This paper introduces a versatile continuous-time capture-recapture model accounting for heterogeneity and behavioral responses, applied to estimate the number of cannabis users in Italy.

Contribution

It presents a novel continuous-time model that incorporates heterogeneity and behavioral effects, with an EM algorithm for population size estimation.

Findings

Effective estimation of cannabis user population in Italy

Model captures delayed behavioral responses

Flexible handling of individual heterogeneity

Abstract

We propose a general and flexible capture-recapture model in continuous time. Our model incorporates time-heterogeneity, observed and unobserved individual heterogeneity, and behavioral response to capture. Behavioral response can possibly have a delayed onset and a finite-time memory. Estimation of the population size is based on the conditional likelihood after use of the EM algorithm. We develop an application to the estimation of the number of adult cannabinoid users in Italy.