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 ...

Survey mode effects linked to unit nonresponse and screening procedures were estimated in a study of self-reported tobacco, alcohol, and illicit drug use. Two samples of the same population were drawn ...

For decades the gold standard for public opinion surveys has been the probability poll, where a sample of randomly selected adults is polled and results are used to measure public opinion across an ...

Statistics are often estimated from a sample rather than from the entire population. If the inclusion probability of the sample is unknown to the researcher, that is, a nonprobability sample, naively ...