Probability-based panel: This refers to a national survey panel recruited using random sampling from a database that includes most people in the population. Today, most such panels in the United ...

To better understand the current landscape of commercially available online nonprobability samples, Pew Research Center conducted a study in which an identical questionnaire was administered to nine ...

An explanation of the methodology for most of 538's current polling averages. Almost since its founding, 538 has published comprehensive averages of polls for a wide variety of questions related to ...