Can You Retroactively Retrieve Prolific IDs in LimeSurvey If Not Configured From the Start ?

Objective

• Understand why Prolific IDs cannot be recovered retroactively.
• Configure LimeSurvey to capture Prolific IDs for future participation.
• Ensure that all new collected data will be properly linked to participants.

1. The limitation: retroactive recovery is impossible

Unfortunately, you generally cannot retroactively retrieve Prolific IDs for data you have already collected if LimeSurvey was not initially configured to capture them.

2. Why this is not possible

When participants click from Prolific to your LimeSurvey study, their unique Prolific ID is transmitted as a parameter in the URL. Think of it as information attached to the web address.

1. LimeSurvey must be instructed to record it : unless you explicitly tell LimeSurvey to "capture" and record this specific information, it simply ignores it. It is like someone giving you a name tag, but you have no pocket to store it in: it is lost.
2. No automatic link after the fact : there is no built-in functionality in LimeSurvey or Prolific that can go back in time and match already-submitted responses with Prolific IDs, if that ID was not recorded at the time of submission.

3. Consequences for your existing data

If your survey has already collected responses without the Prolific ID being saved, those responses will remain unlinked to specific Prolific participants. This makes it impossible to:

• Approve or reject submissions : you will not know which data belongs to which participant, making it impossible to approve payments or reject poor-quality submissions.
• Use Prolific demographic data : without the ID, you cannot link your survey data to demographic information for analysis.
• Track participation : you cannot definitively verify who completed your survey via Prolific.

4. The solution: configure for future participation

The good news is that you can configure your LimeSurvey project to capture Prolific IDs for all future participants. This ensures that all new data collected will be properly linked.

5. Step 1: include the parameter in the Prolific URL

When you set up your study on Prolific, ensure your survey URL looks like this:

https://your-limesurvey.be/index.php/123456?lang=en&PROLIFIC_PID={{%PROLIFIC_PID%}}

The essential part is &PROLIFIC_PID={{%PROLIFIC_PID%}}.

6. Step 2: create a hidden question in LimeSurvey

In your LimeSurvey survey, configure a question to automatically record the Prolific ID:

1. Create a new question in LimeSurvey.
2. Set the "Question type" to "Short text".
3. Go to "Logic" or "Display" settings and hide this question from participants. This way, they will not see it and will not need to interact with it.
4. In the question settings, look for "Default value" or "URL parameter" options. Configure it to automatically load the value of the URL parameter named PROLIFIC_PID.

7. Result

Once this configuration is in place, each new participant coming from Prolific will have their Prolific ID automatically recorded in the hidden question within your LimeSurvey data.

8. Best practices

• Configure this capture from the start : before launching your study, ensure the Prolific URL and LimeSurvey question are properly configured.
• Test the capture : create a test participant on Prolific and verify that the Prolific ID is properly recorded in LimeSurvey.
• Document your configuration : note exactly how you configured the capture for future studies.
• Accept that past data cannot be recovered : if you have already collected data without capture, it cannot be linked retroactively.

Need help?

For any difficulty, contact the LimeSurvey team via: Cellule.Web@ulb.be