title: [The application of network scale-up method on female sex workers and clients size estimation in Taizhou city].
abstract: OBJECTIVE
  To estimate the size of female sex workers and clients in Taizhou city.
  
  
  METHODS
  A household survey using network scale-up method (NSUM) was conducted among the 3000 community residents in Taizhou city from August to October in 2011, which aimed to estimate the social network size (c value) of Taizhou residents, and the c value was adjusted by demographic characteristics, back estimation and outlier elimination. Using the adjusted c value, the number of acquaintance of female sex workers or clients and the respect level toward female sex workers or clients were used to estimate the size of female sex workers and clients.
  
  
  RESULTS
  A total of 2783 valid questionnaires were collected, among which 1380 (49.6%) were collected from Taixing city, 1403 (50.4%) were collected from Jingjiang city. 1334 respondents were male (47.9%) and 1449 (47.9%) respondents were female. The mean age was (39.4 ± 10.7) years. The average personal social network size using original data for Taizhou residents was 525, which differed from place, sex, age, educational level and marriage status. Using the remaining known populations through back estimation, the social network size was 419 and became 424 after the elimination of outliers. The estimated population size for female sex worker was 6370 (95%CI: 5886 - 6853), which accounted for 0.52% (6370/1 229 980) of the total number of female aged from 15 to 49. The estimated population size for clients was 15 202 (95%CI: 14 560 - 15 847), which accounted for 1.28% (15 202/1 190 340) of the total number of males aged from 15 to 49 and the ration of clients to female sex worker was 2.39:1.
  
  
  CONCLUSIONS
  NSUM is an easy and quick way to estimate the size of female sex workers or clients, but the estimated sizes are subject to bias and error due to estimate effect and sample representativeness.
authors.affiliation: Jiangsu Provincial Center for Disease Prevention and Control, Nanjing 210009, China.
authors.forename: Xi-ping
authors.initials: XP
authors.lastname: Huan
authors.forename: Shui-lian
authors.initials: SL
authors.lastname: Bao
authors.forename: Hai-tao
authors.initials: HT
authors.lastname: Yang
authors.forename: Jin-shui
authors.initials: JS
authors.lastname: Xu
authors.forename: Tao
authors.initials: T
authors.lastname: Qiu
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang
authors.forename: Long
authors.initials: L
authors.lastname: Pan
authors.forename: Zhong-kui
authors.initials: ZK
authors.lastname: Zhu
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011477:Sex Work / Q000706:statistics & numerical data*; D060386:Sex Workers / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires; D055815:Young Adult