Pew Research Center designed this study to assess the current state of online survey sampling methods – both probability-based and opt-in – and determine their accuracy on general population estimates ...

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) ...

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 – ...

Stability studies measure how medical devices respond to environmental stresses such as temperature, humidity, light, and ...