Non-invasive sampling methods include saliva analysis, hair analysis, urinalysis, and breath testing. <br/>The importance of ...

verybody has a favorite color and season—preferences that seem innate, always defying reason. Auditors are no different when it comes to haphazard sampling, a process in which—ideally—they choose ...

Pew Research Center is committed to meeting the highest methodological standards — and to exploring the newest frontiers of research. Learn more about the methods the Center uses to conduct objective, ...

Survey researchers increasingly recognize that a single survey of the general public can rarely represent the views of small groups of Americans. Such surveys frequently have too few interviews with ...