In web surveys, no interviewer is present to clarify question comprehension problems, which can be particularly prevalent among respondents with low literacy skills. Although plain language is used in various contexts to improve text comprehensibility, its use in social science questionnaires has not been investigated to date. Using a…

Randomized experiments involving education interventions are typically implemented as cluster randomized trials, with schools serving as clusters. To design such a study, it is critical to understand the degree to which learning outcomes vary between versus within clusters (schools), specifically the intraclass correlation coefficient. It is also…