How to Detect Duplicate Responses

Use respondent IDs and URL parameters to identify repeated completions.

The Short Version

Use respondent IDs and URL parameters to identify repeated completions. A practical way to begin is to pass stable respondent IDs through the URL when available, then fetch fielded results. Finish by making sure you document the rule in methods text. The full walkthrough below explains each part in order.

Is This Guide for You?

Researchers fielding public links or panel studies.

Follow These Steps

Work through these 5 steps at your own pace. The wording is intentionally practical, and you can return to the checklist at the end when you are ready to review your work.

Pass stable respondent IDs through the URL when available.
Fetch fielded results.
Review duplicate counts.
Use exclusion rules if duplicates should be removed.
Document the rule in methods text.

What This Helps You Accomplish

Duplicate responses can distort estimates and create payment disputes. Detection is easier when respondent IDs are captured at start.

A Quick Confidence Check

Use Prolific or worker IDs when available.
Do not rely only on IP address.
Keep the first completed response unless your preregistration says otherwise.

Common Questions

Can I use this guide if I am new to this?

Yes. Researchers fielding public links or panel studies. Follow the steps in order, start with a small test, and use the final checklist before you field or report anything important.

What is the simplest way to get started?

Begin by pass stable respondent IDs through the URL when available. Next, fetch fielded results. You do not need to perfect every setting before running a small preview or pilot.

How do I know when I am ready?

Use the confidence check above. In particular: Use Prolific or worker IDs when available. Do not rely only on IP address. Keep the first completed response unless your preregistration says otherwise. When the decision is consequential, keep your study documentation and ask a qualified colleague or methods reviewer to examine the design as well.

Research Pathways

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