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

Thermo Fisher Scientific introduces the Thermo Scientific™ Sequential Protein/DNA/RNA Extraction Kit, a sample preparation solution designed to enable the sequential extraction of protein, DNA and RNA ...

By Courtney Kennedy, Andrew Mercer, Scott Keeter, Nick Hatley, Kyley McGeeney and Alejandra Gimenez As the costs and nonresponse rates of traditional, probability-based surveys seem to grow each year, ...

Power analyses and sample size calculations are important parts of many research projects. Often, before data are even collected, it is necessary to calculate and justify the required sample size for ...

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 ...