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 ...

In a simple random sample, each individual in the population has an equal probability of being chosen. Additionally, each sample of size n has an equal probability of being the chosen sample. This ...

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 ...

Prasanta Chandra Mahalanobis, the Indian statistician who founded the Indian Statistical Institute and pioneered large-scale sample survey methodology, changed how the world collects data. His methods ...

Sampling is the process of collecting some data when collecting it all or analyzing it all is unreasonable. Before addressing why sampling still matters when massive amounts of data are available and ...