Department of Epidemiology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, PR China.
OBJECTIVE: To ascertain practical methods of estimating the population size of men who have sex with men (MSM) by field application. METHODS: Nine public places were selected, where men who have sex with men (MSM) frequented. Capture-recapture method and multiplier method were used to count the number of men who have sex with men (MSM) in the assigned places in 10 days. RESULTS: The population size estimated using multiplier method counted 877. Three estimates produced by capture-recapture method were 1408 (95% CI: 1116-1908), 1207 (95% CI: 932-1712) and 949 (95% CI: 757-1272), respectively. CONCLUSIONS: Multiplier method was easy and smooth in practice and produced highly reliable results, which yet was expensive. The application of capture-recapture method cost less in both time and funds, and the three results produced could verify each other, which was fit for the estimation.