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 ...

Survey questions raising concerns in middle schools: *The last time you engaged in sexual activity, did you use one of the following to protect yourself from sexually transmitted diseases (STDs)?

Historically, public opinion surveys have relied on the ability to adjust their datasets using a core set of demographics – sex, age, race and ethnicity, educational attainment, and geographic region ...