A simple random sample is a subset of a statistical population where each member of the population is equally likely to be ...

Stratified random sampling is a method of sampling that divides a population into smaller groups that form the basis of test ...

Historically, public opinion surveys have relied on the ability to adjust their datasets using a core set of demographics – sex, age, race and ethnicity, educational attainment, and geographic region ...

Although 24-h urine collection is widely considered the ’gold standard’ for estimation of population sodium intake, spot urine collection is increasingly used as a convenient and affordable ...

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 ...