Sample surveys versus experiments, controlled observations, censuses, registers, and local studies.
D003625:Data Collection; D005069:Evaluation Studies as Topic; D010865:Pilot Projects; D011154:Population Characteristics; D012106:Research; D012494:Sampling Studies; D014798:Vital Statistics
Comparative Studies; Data Collection; Data Sources; Evaluation; Pilot Projects; Population Statistics; Research Methodology; Sampling Studies; Studies; Surveys; Vital Statistics; World