Screening that finds your people fast.

The cheapest screening happens before anyone clicks your link. Panel platforms hold rich prescreening data — demographics, languages, employment, devices — and filtering there costs nothing and wastes nobody's time. Use it for every criterion the panel can express.

Your own screener exists for the criteria the panel cannot know: behavior (“grocery shopped online in the past month”), ownership, experience with a specific product, a clinical population. Put those questions on the first page, route ineligible answers to the screen-out immediately, and only then let the real survey begin. Screening on page one instead of page five is the single biggest cost lever you control.

To reduce the chance of someone guessing the answer that qualifies, include plausible alternatives without naming the eligibility rule.

The second version reads like a demographic question. The person who qualifies doesn't know which option mattered, and neither does the person who doesn't. For higher-stakes eligibility, verify with a follow-up only a genuine member of the group answers easily — an EV owner knows roughly where they charge; a faker improvises.

Ask only the questions needed to establish eligibility. Longer screeners take more participant time, especially for people who will not qualify.

Quotas limit responses in each segment, such as 100 per condition or no more than 40% from one age band. Check how the tool enforces limits and handles people who reach a full quota:

Enforcement must be server-side and race-safe. Panels deliver participants in bursts; when the last slot of a cell has thirty people mid-survey, client-side counting oversubscribes it every time. The count-and-close has to happen atomically at the database, not in the browser.

Full cells should turn people away early. The respectful version of “quota full” happens at the first qualifying answer, not after the last page. In Plumeform, quotas are conditions with a limit; full segments screen out at the page boundary where they qualify, the enforcement runs inside the database under a lock, and screened rows never count against your response cap or monthly limit.

Report a full quota as over-quota. Sample vendors usually give you three return links: complete, terminate and over-quota. Someone turned away by a full cell qualified, so sending them to the terminate link understates your incidence rate. In Plumeform, a full quota has its own code and redirect; without one, it uses the screen-out exit, which is all Prolific needs.

People who do not qualify still need a clear ending and the payment treatment required by your panel. Resolve their submission properly: give them the panel's screen-out exit (a separate completion code and redirect) so their status resolves instead of hanging at awaiting review; never reject someone for failing to be eligible. Use a courteous exit message, such as “This study needs a specific mix of participants, and you do not qualify for this one. Thank you for your time.”