Mathematics
Randomness creates certainty
A poll of 1,000 people predicts what millions think because a fairly drawn sample's average settles close to the true population share, whatever that population's size. Pew Research's own methodology page asks this exact question: can 1,000 people speak for over 250 million U.S. adults? Only if the sample is unbiased.
Sources & further reading
American Mathematical SocietyIntroduction to ProbabilityThe textbook definition of the law of large numbers.Pew Research CenterHow Pew Research Center conducts its U.S. surveysHow a small, fair sample can stand in for millions of people.HyperPhysics, Georgia State UniversityKinetic Theory of GasesHow the random motion of many particles produces steady pressure.Insurance Information InstituteUnderstanding how insurance worksHow insurers pool many policies to estimate total claims.
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