Cowlitz County health officials may random sample 400 residents to better understand the prevalence of COVID-19 in the community. Dr. Steve Krager, county health officer, presented the county ...

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 ...

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 – ...