Screener
Also called screening questions, eligibility questions
The questions at the start that decide whether somebody belongs in the study, and route them accordingly.
A screener turns inclusion criteria into questions about behavior, role, experience or age. Avoid revealing which answer qualifies, especially when an incentive could encourage someone to guess.
Write neutral questions with plausible alternatives and a genuine none-of-these option, and spread the criteria across separate items rather than asking one question that gives the game away. Then route: eligible participants forward, everybody else to a clear, respectful ending.
Test every path before recruiting, including the combinations you think are impossible, and check what the export actually recorded for a screened-out participant.
Where it goes wrong
Paid panels. When qualification is linked to payment, the incentive to answer strategically is strongest, and a transparent screener will over-qualify.