The first video in Pew Research Center’s Methods 101 series helps explain random sampling – a concept that lies at the heart of all probability-based survey research – and why it’s important. Fresh ...

Imagine you're tasked with sending a team of football players onto a field to assess the condition of the grass (a likely task for them, of course). If you pick their positions randomly, they might ...

The COVID-19 pandemic has infected over 38 million people around the world and is showing no signs of going away any time soon. Researchers worldwide are frantically working on developing an effective ...

Journal of the Royal Statistical Society. Series C (Applied Statistics), Vol. 42, No. 4 (1993), pp. 585-601 (17 pages) In this paper two-dimensional systematic sampling of land use is considered. Data ...

When investigators think of generalizability, they typically think of extrapolating the results to other patient populations, depending on whether patients were selected for the study by means of ...

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 ...