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 ...

Passive sampling techniques have emerged as indispensable tools in the monitoring of environmental pollutants. These methods involve the in situ accumulation of contaminants over extended periods, ...

Detailed information on Pew Research Center international survey meethodology, such as mode of interview, sampling design, margin of error, and design effect, for each country we survey, organized by ...

Learn how acceptance sampling improves quality control by evaluating random samples. Discover its methods, benefits, and historical significance in manufacturing.