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 ...

With a population of over 40 million users worldwide, a number doubling every year, the internet has become a medium with distinct business opportunities. To academic and commercial researchers, the ...

Survey sampling and estimation methods form the cornerstone of modern statistical inference, underpinning research across the social, medical, and natural sciences. At their heart, these methods ...

The nuts and bolts of our public opinion surveys. A summary of ABC News' polling standards and survey methodology follows. ABC News maintains standards for disclosure, validity, reliability and ...