Ways to tie participants responses

Question

So I have two questionnaires, one is hosted on Qualtrics and the other is on REDCap. The participants first fill out the questionnaire on Qualtrics and then gets redirected to the REDCap questionnaire. Neither of these questionnaires collect any identifying information (names, email, etc.). Are there any ways/methods to tie the responses together besides comparing the timestamps of the submissions which could sometimes be inaccurate. I appreciate any input/advice.

I have already asked this question on the Qualtrics community site as I know this is not a programming related question but I am asking here anyway as I require a solution quickly.

Answer 1

TomG's answer on the Qualtrics forum will work for you. All you need to do is configure a field in REDCap to receive that data passed in via the query string.

Qualtrics provides the ResponseID field for this, which when sent to REDCap will allow you to link records from both platforms.

In Qualtrics, configure the URL directing your participants to REDCap by piping in the ResponseID as follows:

https://REDCAP_BASE/surveys/?s=SURVEYID&qualtrics_response_id=${e://Field/ResponseID}

In REDCap, add a field to your instrument that has the variable name qualtrics_response_id (or whatever you choose). When a participant clicks through, their Qualtrics response ID will be stored in the REDCap variable.

For extra functionality/security, you can hide the field in REDCap using the @HIDDEN or @HIDDEN-SURVEY action tags (I suggest the latter so you can still see it in the form; the value will be included in the data regardless), or display it but prevent the user from modifying it with the action tag @READONLY.

Here's a screenshot demonstrating the latter. The field 'some question' has the var name q, hence the query string q=blah.