Sampling is a type of scientific surveying which can save time and money and give information on the population of animals and plants. There are many different types of sampling; the most useful type ...

Bees (family: Apidae) are important ecologically and economically as primary pollinators of many natural and agricultural systems. Given current concerns about declining numbers of bees, many ...

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 ...

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 ...

Systematic sampling is straightforward and low risk, offering better control. However, it may introduce sampling errors and ...