Sample sizes were calculated separately for Myanmar migrants and Cambodian migrants with the assumption that the social networks of the two groups are independent. As the main objective of the study was to estimate the proportions of M1 or M2 among the Cambodian and Myanmar migrant workers in the study areas and there has been no clear sampling frame, the sample sizes were calculated using a conservative target proportion of 50% with a confidence level of 95% and a confidence interval of 0.45, 0.55. A design effect of 2.0 and a non-response rate of 10% were adopted. A sample size of 900 participants for each of the two groups (total 1,800 participants) was required.