Recruitment is generally the first contact between researchers and prospective participants (whether through paper-based or online announcements, media communications, or face-to-face interactions) ...

Proper quality measures are vital in all areas of clinical laboratory testing to prevent or avoid carryover between samples, as well as to minimize the risk of false-positive results. The sample ...

This study looks at how national public opinion polling in the United States changed from 2000 to 2022. It focuses on two aspects: the sample source(s) – that is, where the survey takers came from – ...

Pew Research Center is committed to meeting the highest methodological standards — and to exploring the newest frontiers of research. Learn more about the methods the Center uses to conduct objective, ...