In a typical year, several thousand samples from flu patients around the world arrive at the U.S. Centers for Disease Control and Prevention. They're crucial for understanding the virus's evolution ...

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 ...

Providing samples to customers is an important promotional tool for many businesses, and they are often used to encourage an immediate or future purchase. The way the sample is offered and contributes ...