One possible explanation for the variability in estimates across the different nonprobability samples is the range of methods that online sample vendors employ. They differ on recruitment, weighting ...

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 ...

A sample survey has many potential sources of error that generally have a systematic effect on the outcomes. Therefore, many large-scale field experiments are ...