If you are planning a research project, or just curious to learn more about research, you can use this guide to get an overview of some key terms. However, research methods vary hugely across ...

Pew Research Center designed this study to assess the current state of online survey sampling methods – both probability-based and opt-in – and determine their accuracy on general population estimates ...

This study looks at how national public opinion polling in the United States changed from 2000 to 2022. It focuses on two aspects: the sample source(s) – that is, where the survey takers came from – ...

BACKGROUND: Induced abortion is a common procedure performed by physicians with varying degrees of clinical experience. We aimed to determine whether a physician’s procedure volume influences ...