Little is known about migratory patterns along the Thailand-Cambodia border. However, given the hidden and mobile nature of these populations and the difficulty in generating a sampling frame, traditional sampling techniques such as cross sectional communitybased surveys or time-location sampling are unable to produce an adequate and statistically valid sample.
Respondent driven sampling (RDS) is a modified form of chain-referral or snowball sampling that has been used to sample hidden populations [9-12], and seeks to overcome the biases in traditional snowball sampling.
It uses a structured system of incentives to encourage recruitment by peers while limiting the number of individuals each participant can recruit, records the size of each participant’s network to weight the sample, and enables calculation of sampling error [9-11], thus allowing
for inferences about the characteristics of the population from which the sample is drawn. Pre-survey focus group discussions were held with migrants from Cambodia and Myanmar to assess the feasibility of using RDS.
Discussions focused on migrants’ links to and relative size of social networks, willingness to participate, and potential barriers to participation such as limitation of local travel due to lack of transportation or poor roads, a burdensome work schedule, or fear of authority figures.