Figure 6.

Structure of a survey experiment with blending. Respondents from the sample are randomly placed in one of 2 arms, and a different variation of the scale-up method (in our case, a different definition of a social tie) is used in each arm. Researchers can learn about which experimental condition performs better by comparing estimates of the known quantities with their actual values. Researchers can produce substantive size estimates for hidden populations by blending the results from each arm together.