How can I contact subjects by pseudonym after the study is finished?

Finding subjects by pseudonym is no longer possible once the study has finished. If you need to contact a subject after the study is finished we recommend to resume the study temporarily.

How can I edit subject data as recruiter or study conductor?

Recruiters and conductors are only allowed to access subject data of participants within study context. Yet, this workflow allows to edit the subject data of them:

  • Search for the participant via Subjects on the home screen.

  • Select either Recruitment or Execution (whichever is applicable) in the Matches list to go to the subject details view.

  • Click on Update data and select appropriate categories that need to be edited. Edit and save the forms accordingly.

Although it has a slightly different look and feel you can get reference on editing subject data here: Edit Subject Data.

What should I do if a subject doesn’t show up for their appointment?

Castellum allows you to mark a subject as unreliable. In our experience, many unreliable subjects are not aware how expensives no-shows can be. Contacting them and explaining the situation can help avoiding no-shows in the future.

How can I use pseudonyms with LimeSurvey?

  1. In LimeSurvey, add a new question called “pseudonym” and hide it (Display - Always hide this question)

  2. In Castellum, add a new Pseudonym List called “LimeSurvey”.

  3. Send a personalized LimeSurvey link to each participant. For example: If the participant’s pseudonym is “abc” and the basic LimeSurvey link is https://example.limesurvey.net/123456?lang=de, the personalized link is https://example.limesurvey.net/123456?lang=de&pseudonym=abc.

  4. After the participants have answered the questionnaire, go to LimeSurvey and click on Responses to download the data. The pseudonyms will be included as the output of the hidden field “pseudonym”.

  5. In Castellum, find the subject for each pseudonym to link the questionnaire results to your other data.


It is important to use a separate pseudonym list because the pseudonyms are sent out along with the name and email address. Anyone who has access to that email (e.g. many people working at the company that provides the email account) will be able to match this pseudonym to the real person.