Running a Longitudinal Study in Qualtrics

This article will help Qualtrics survey designers understand how to create a longitudinal study.  

Unlike a one-time use survey, longitudinal designs record repeated observations from the same subject over some period of time.  In this example, participants in one of three groups are sent a new survey every morning over the course of ten days.  Each day's survey contains instructions specific to its group and expires that evening.  Our goal is to use more advanced Qualtrics features to partly automate this process and to track how many of the ten days each subject participated in a survey (subjects are allowed to skip days and then resume).

Create a Contact List

Create a new Contact List and leave it empty for now.

Set up an Opt-In Survey

This case study consisted of an initial opt-in survey, followed by ten days of follow-up surveys.  We obtained participants from the Wharton Behavioral Lab (WBL) for this study.

1.  In the survey flow, create an embedded data field named Days with an initial value of 0.
2.  Randomize Group conditions using a randomizer in the survey flow.
3.  Create a text-entry question in your survey asking for participants' email address.
4.  Create a contact list trigger.
   1. Select the contact list created at the beginning of this process.
   2. Select Update Existing List Members.
   3. Choose source of Email field from text entry question in Step 3.
   4. Add fields Days and Group and set them equal to the embedded data fields Days and Group.
   5. Set Survey activation/expiration time frame in Survey Options.Note: The timezone in Qualtrics projects is often (but not always) MST/MDT.  Make sure to check the timezone and account for this when setting activation periods.

Setting up the Additional Surveys

The ten additional surveys all follow the same general format.  Complete the following steps on all of the surveys.  

1.  Increment the Days variable by 1 to count this day's participation.  Use math operations on the embedded data in survey flow like this:
   Days = $e{ e://Field/Days + 1}.
    
2. Create a trigger to update your contact list.
3.  Set expiration times for your survey under Survey Protection as described in Step 5 of the opt-in survey.

Email Survey Links

When your surveys are ready to go, you can schedule a distribution via email.  

1.  Go to the Distributions tab, select Email, then Compose Email.  
2.  Select your contact list next to the To label.
3.  Set your desired From and Subject field values.  Add any additional Message content.
4.  Next to When, select Custom and then the date and time you want the link sent.
5.  Send yourself a preview and then schedule your email.

Displaying the Day Count

Optionally, you may want to display to your subjects how many days they've participated so far.  This is easily accomplished using piped text.  

1.  Create a question in your survey and in its label write something like You have participated, then select Piped Text in the label editor followed by Embedded Data Field.  You may now either type or select the field named Days and finish the message text.  
2.  The final label text will look something like this. 
3.  Click Preview to see the piped text field replaced by its value.  

Questions?

Email: research-programming@wharton.upenn.edu