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9 min read

Find responses that need a closer look.

Unusually fast responses, repeated answer patterns and duplicate text can signal a quality problem. Each can also have an innocent explanation. Record the signals, review them together, and apply exclusion rules you decided on before looking at the results.

Speeders: finished before they read

The single most useful quality signal is time. A person who genuinely reads and answers a ten-minute survey cannot finish it in ninety seconds; someone chasing a payout can. Record the duration of every response and you can see the racers as a cluster far below everyone else.

Fixed thresholds are fragile because they depend on your survey, so compute the cutoff from your own data: take the median completion time of real responses and flag anything below roughly a third of it. Plumeform does this automatically once a handful of timed responses are in, and marks the speeders for you.

What a speeder looks like

Median completion time: 6m 40s

  • Most responses: 4 to 11 minutes
  • A cluster at 40 to 70 seconds: review these
  • One response at 38 minutes: the participant may have paused

Straight-liners: the same answer, all the way down

Someone may choose the same point for every row of a rating matrix. This pattern is called straight-lining, and it is invisible in a summary chart because the answers are perfectly valid values.

You catch it by looking at the variance within a single response. Repeated answers across a long battery deserve review, especially when items differ in meaning. They can also reflect someone’s views, so check the wording and other quality signals before excluding the response.

Bots and duplicates: the same response, twice

Automated and repeat submissions cluster. The same option pattern, the same suspiciously round timing, often the same referrer, arriving in a burst. Open-text answers are the giveaway: generic, off-topic, or copied verbatim across “different” people.

Do

  • Use a one-response-per-browser limit for casual, uncompensated sharing.
  • Pass a unique participant ID from your panel and reject repeat IDs.
  • Cap total responses so a leaked link can't run up an unlimited bill.
  • Add a short open-text question; junk answers are easy to spot by eye.

Don't

  • Don't rely on IP alone; shared networks and VPNs make it noisy.
  • Don't put the incentive amount in the invite; it recruits the wrong people.
  • Don't assume a completed response is a real one. Completeness is not quality.

Attention checks: was anyone reading?

An instructed-response item asks someone to select a named answer, such as Disagree. Use clear instructions and review a failure alongside timing and answer content.

Attention checks pair with everything above: a response that speeds, straight-lines, and fails a check deserves closer review. Our attention-check guide explains how to write and use these items.

Flag, don't delete on a hunch

Before collecting data, decide your exclusion criteria before you see the results. Keep the original data, mark the flagged rows, and apply those rules consistently. Changing exclusions to suit a result can bias the analysis.

In Plumeform every response carries its quality flags, and a single filter hides the flagged ones so you can see your results clean and dirty side by side. If the story is the same either way, you can report it with confidence; if it changes, that is worth knowing before you present it.

Quick answers

How do I know if survey responses are fake or careless?
Look for four signatures. Speeders finish far faster than any careful reader could. Straight-liners pick the same column down a whole matrix. Failed attention checks mean the words were not being read. And duplicate or bot submissions cluster: the same answers, the same timing, often the same source. No single flag is proof, but two or more on one response is a strong signal to set it aside.
What is a speeder, and how fast is too fast?
A speeder is someone who completes the survey too quickly to have genuinely read it. A common rule is anything under roughly one third to one half of the median completion time. Because that threshold depends on your own survey, it is better computed from your data than fixed in advance: take the median duration of real responses and flag the ones far below it.
Should I delete low-quality responses?
Flag first, decide later, and write the rule down before you look at results. Deleting on a hunch after you have seen the answers invites bias. The defensible pattern is to keep every response, mark the flagged ones, and report your data both with and without them so a reader can see the cleaning didn't change your conclusion.
How do I stop one person submitting a survey many times?
For casual sharing, a one-response-per-browser setting stops the honest double-submit. For anything with an incentive, add a unique participant ID from your panel and reject duplicates on it, cap total responses, and use screening plus quotas so a filled segment stops accepting. Nothing is bulletproof against a determined bad actor, but layered friction removes the easy abuse.

Keep reading: Review attention and timing signals · Writing attention checks · How many responses you need · Stopping duplicate participants

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