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 ...

Medical research plays a vital role in advancing healthcare, improving treatment, and informing public health policies. However, it can be difficult to understand a study or whether it is trustworthy.

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 – ...