Busaba Suppawattanabodee. Estimating the number of drug users in Bangkok : a capture-recapture method . Master's Degree(Biostatistics). Mahidol University. : Mahidol University, 2003.
Estimating the number of drug users in Bangkok : a capture-recapture method
Abstract:
The purposes of this study were to estimate the number of drug users in
Bangkok and to investigate the percentage of under-reporting number of drug users
from two sources. The data were taken from two sources: 61 health treatment centers
and 88 police stations in Bangkok during the period of 3 months from October 1 to
December 31, 2001. A capture-recapture method was applied to estimate the total
number of drug users.
The study revealed that match type A+B+C+D was considered to be a true
match and met three assumptions. By this standard, it yielded an estimate of 427,933
(SE = 23,456, 95%CI = 381,958 - 473,907) drug users in Bangkok. As for the
percentage of under-reporting, 97.38% were from the health treatment centers source,
and 97.19% from the police stations source. The finding revealed that the estimate
might be confounded with some factors. Stratified analysis was done and the study
revealed that match type A+B+C+D after stratification by type of drugs was
considered to be the best estimate, with an estimate of 232,966 (SE =1,722, 95%CI =
229,591- 236,340). However, the variance of the estimates was still large, and the
alternative method depending only on one source of the health treatment centers
source which proposed the mixture distributions of the truncated Poisson models was
done. By this method, there was an estimate of 44,380 of drug users in Bangkok. The
results of this study suggest that other estimation methods, Log-linear model, Bayesian
estimator, and Zero-inflated model should be applied.