Note: This report was updated on Dec. 30, 2015 to reflect the January-July 2015 National Health Interview Survey estimates released on December 1, 2015. Telephone surveys face numerous challenges, but ...

It's not feasible to contact every member of the population, so only a sample, or a subset, of that population is included when conducting statistical research. The assumption is that the sample is ...

Sean Ross is a strategic adviser at 1031x.com, Investopedia contributor, and the founder and manager of Free Lances Ltd. Gordon Scott has been an active investor and technical analyst or 20+ years. He ...

In a recent study published in Nature Medicine, researchers created the REP-EQUITY toolbox for capturing an equitable and representative sample for health research studies. Research participants are ...

New research has led to a model that assesses the short- and long-term effects of in-store product sampling on sales of both the products offered on sample and competitive products. In big box stores, ...