background : a detailed study of hidden and hard to reach populations in order to identify their characteristics is essential because they endanger the health of the society by their dangerous behaviors. however, sampling in these populations through conventional sampling methods is impossible due to reasons such as being hidden and lacking a precise frame. methods: in this article, applicable ...

BACKGROUND In Zanzibar, a semi-autonomous region of Tanzania, induced abortion is illegal but common, and fewer than 12% of married reproductive-aged women use modern contraception. As part of a multi-method study about contraception and consequences of unwanted pregnancies, the objective of this study was to understand the experiences of Zanzibari women who terminated pregnancies. METHODS Th...

BACKGROUND Smoking is the number one preventable cause of death in the United States. Effective Web-assisted tobacco interventions are often underutilized and require new and innovative engagement approaches. Web-based peer-driven chain referrals successfully used outside health care have the potential for increasing the reach of Internet interventions. OBJECTIVE The objective of our study wa...

Recruiting samples that are more representative of illicit drug users is an on-going challenge in substance abuse research. Respondent-driven sampling (RDS), a new form of chain-referral sampling, is designed to eliminate the bias caused by the non-random selection of the initial recruits and reduce other sources of bias (e.g. bias due to volunteerism and masking) that are usually associated wi...

Respondent driven sampling (RDS) is a network sampling technique typically employed for hard-to-reach populations (e.g. drug users, men who have sex with men, people with HIV). Similar to snowball sampling, initial seed respondents recruit additional respondents from their network of friends. The recruiting process repeats iteratively, thereby forming long referral chains. Unlike in snowball sa...

BACKGROUND Sampling in the absence of accurate or comprehensive information routinely poses logistical, ethical, and resource allocation challenges in social science, clinical, epidemiological, health service and population health research. These challenges are compounded if few members of a target population know each other or regularly interact. This paper reports on the sampling methods adop...

Studies of populations such as drug users encounter difficulties because the members of the populations are rare, hidden, or hard to reach. Conventionally designed large-scale surveys detect relatively few members of the populations so that estimates of population characteristics have high uncertainty. Ethnographic studies, on the other hand, reach suitable numbers of individuals only through t...