Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Representative sampling and random sampling ...

Greg DePersio has 13+ years of professional experience in sales and SEO and 3+ years as a writer and editor. Robert Kelly is managing director of XTS Energy LLC, and has more than three decades of ...

A study by the universities of Cordoba and Seville develops a method that makes it possible to verify, easily and quickly, whether an olive plantation is traditional, intensive, or super-intensive.

Oct. 8, 2008— -- Surveys based on a random sample of respondents are subject to sampling error – a calculation of how closely the results reflect the attitudes ...

Imagine you're tasked with sending a team of football players onto a field to assess the condition of the grass (a likely task for them, of course). If you pick their positions randomly, they might ...

Survey researchers increasingly recognize that a single survey of the general public can rarely represent the views of small groups of Americans. Such surveys frequently have too few interviews with ...