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

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, ...

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 ...

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 ...

One of the claimed advantages of RBS surveys is their efficiency. Unlike RDD surveys, which rely on lists of potentially working telephone numbers, RBS surveys use lists of actual Americans. Despite ...