Water Environment Research, Vol. 64, No. 7 (Nov. - Dec., 1992), pp. 866-876 (11 pages) Stream sampling for water quality data has commonly employed simple surface-grab procedures as opposed to more ...

Here at Pew Research Center, we are often asked about how we conduct our research. We work hard to make our methodologies transparent and understandable, but we also know that survey mode effects and ...

The first video in Pew Research Center’s Methods 101 series helps explain random sampling – a concept that lies at the heart of all probability-based survey research – and why it’s important. Fresh ...

Information on Earth's biodiversity is increasingly collected using DNA-, image- and audio-based sampling. At the same time, ...