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How do I ask custom screening questions?

We are currently testing this feature for a limited time and it is therefore only available to some researchers. If it is available to you, you will be able to see this in your study setup page. If you don't see this in your study set up page, you can read about how to recruit custom samples here: How do I recruit a custom sample?

As we are testing this feature, we would love to get your feedback and any suggestions to improve the experience. Please let us know your thoughts in this short survey.

Setting up a study

We recommend using custom completion codes to ask custom screening questions in your survey. You can find more details on custom completion codes here: Custom completion codes.

These can be used in your survey tool to divide participant responses into different groups. For screening this can be particularly useful, as you can provide two custom completion codes, one for your screened in participants, and one for screened out participants. This will be helpful once the submissions roll in.

Head to your external survey software and set up the relevant Prolific custom completion codes as a redirect link based on your survey logic. If you need some help, our integration guides have specific instructions for the most common survey software.

In our study set-up page, you will be asked if you are going to ask custom screening questions in your study. By selecting yes, we will generate a “Screened Out” custom completion. Add this to your external survey at the point your screened out participants will conclude the survey and need to come back to Prolific to complete their submission.

You may need to survey quite a large number of participants in order to achieve your desired sample size for the main study. Please note that because we do not hold this data about participants we are unable to estimate the number of eligible people.

Recommended formatting

When it comes to asking custom screening questions in your survey, we recommend keeping your questions vague so that participants are not influenced to answer a certain way. One method is to ask a variety of questions so that the participants don't know which one you're actually measuring. You could, for example, ask the following questions with 'yes/no' answer options:

  • "I live in the UK"
  • "I'm Catholic"
  • "I use an electric toothbrush"
  • "I run regularly"
  • "I have a pet dog"
  • "I have at least 2 uncles"

You can then adjust your questions and format the answers to what works best for you.


It’s important to reward screened out participants for their time spent on your study. The minimum amount is £0.10, in line with Prolific’s payment principles, but you need to take the complexity and length of your custom screening questions into account.

The reward for screened out participants is not included in the cost of your study. Similar to bonus payments, rewarding screened out participants happens on the submission page, and will use budget from your workspace wallet.

Managing submissions

With your two completion codes applied to your study, you will see completed submissions coming through for participants that are either “COMPLETE” or “SCREENED OUT”.

For participants with the latter completion code, select the participant and use the new “Screen out” button.


This enables you to reward participants for their time to complete the screening questions, but not the full reward for the study. Enter the reward amount relative to their time to complete, making sure it meets the minimum of £6/$8 per hour.

Screened out participants are considered complete submissions, and their places will not be reopened automatically for new participants. If you have screened out participants and need more submissions, you can use you can use the existing increase places feature.

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