In the second stage, a similar number of people should be interviewed in each urban tract.
The World Health Organization-recommended sampling technique with probabilities proportional to size was used to select the subjects to be interviewed23, 24. For the first stage, 10 out of 37 urban tracts were randomly chosen. In the second stage, a similar number of people should be interviewed in each urban tract. As a result, there was a lower likelihood that a specific person would be sampled23 in a larger urban tract.