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Longitudinal studies

A longitudinal study is an ordered set of surveys that the same participant is expected to complete sequentially. Typical use cases include pre/post experimental designs, multi-wave panels, or any research where a participant must go through several surveys in a specific order over time.

Unlike the Dashboard of Surveys feature (Section 11), which is designed for snowball distribution where the participant sees a central page with all assigned surveys, Longitudinal Studies are designed for panel-based distribution: each survey is distributed independently by the panel provider (Netquest, Cint, TickPanel, etc.) using its own URL + user id, one at a time.

The key guarantee of a longitudinal study is that a participant cannot access survey N until they have completed all previous surveys (1 to N-1) of the same study. This is enforced on the server: even if the participant saves the link to survey 3 and tries to open it directly, the system will reject them with an early screen-out message until they complete steps 1 and 2.

15.1 Creating a study

  1. Open Long. Studies in the left menu and click My studies.
  2. Click New Longitudinal Study at the top.
  3. Fill in:
  4. Name: a short label shown in listings and statistics (required).
  5. Description: a longer explanation of what the study is about (optional).
  6. Click Create study. The system opens the study in edit mode so you can start adding surveys.

A study has a single owner (the researcher who created it). Other researchers cannot see or edit it, except superadministrators who have full visibility across the platform.

15.2 Adding and ordering surveys

Once the study exists, the Surveys in this study panel appears. From there:

  • Use the Add a survey dropdown to pick one of your own surveys. Only surveys that are not already assigned to another longitudinal study are listed. Click Add; the survey is appended to the list with the next available step number.
  • Drag and drop any survey in the list to change its step order. Changes are saved automatically.
  • Click the × icon on the right of a survey to remove it from the study. The survey itself is not deleted — it simply becomes available again for other studies.

Each row shows the survey's current lifecycle status (Open, Closed, Paused, Programming). The lifecycle of each survey is managed in the normal survey editor; longitudinal studies do not duplicate that concept.

A survey can belong to at most one longitudinal study at any given time.

15.3 How prerequisites are enforced

When a participant opens the URL of a survey that is part of a longitudinal study:

  • If the survey is step 1, the participant proceeds normally.
  • If the survey is step 2 or later, the system checks that the participant has a completed (status Done) record for every previous survey of the study.
  • If any prerequisite is missing, the participant is redirected to a localized message explaining that they must complete the previous surveys first. The rejection is recorded in the study statistics.
  • Rejections are temporary: they do not write an Early Screen Out record in the regular respondent table. Once the participant completes the missing prerequisite surveys, they can re-enter and proceed normally. At that point the earlier rejection record is removed from statistics to avoid double-counting the same participant as both a screen-out and a completion.

The check runs before any other survey-level filter (quotas, exclusions, etc.), so you can rely on it to protect the integrity of your study's flow.

Note that deactivating or closing a survey that participants have already completed does not invalidate those completions; the prerequisite check is based on the historical Done status, not on the current survey state.

15.4 Distributing the surveys

Each survey of a longitudinal study is distributed independently, using its own survey URL with the participant's user id — exactly the same way you would distribute any other survey through a panel. There is no special "study URL"; the study concept is transparent to the participant.

A typical wave-based workflow:

  1. Distribute survey 1 via the panel. Wait until your target sample size is reached or a deadline passes.
  2. Close survey 1 in its editor (so no more respondents can start it).
  3. Distribute survey 2 to the same set of panelists. Only participants who actually completed survey 1 will pass the prerequisite check.
  4. Continue with the remaining surveys.

This approach lets you control the timing between waves (for example, by waiting a fixed number of days between distributions) without any additional configuration in the platform.

15.5 Study statistics

On the study listing, click the chart icon next to a study to open the Study Statistics page. It shows, for each survey of the study:

  • Step: the order of the survey within the study.
  • Survey: the survey name.
  • Status: the current lifecycle status (Open, Closed, Paused, Programming).
  • Completed: number of respondents who finished this survey.
  • vs previous step: the retention rate between consecutive waves — completed[step N] / completed[step N-1] * 100. Step 1 shows — (no previous step). If the previous step has 0 completions, the cell also shows — to avoid division by zero.
  • In progress: number of respondents currently inside this survey.
  • Screen outs: number of respondents rejected before completing, including those blocked by the longitudinal prerequisite check and by the survey's own filters.

A totals row at the bottom aggregates the three numeric columns. Use the Edit study button to jump back to the editor, or Back to list to return to the study listing.

Reset screen-out test data. The Study Statistics page also includes a Reset screen-out test data button. This clears all longitudinal prerequisite rejections for every survey in the study — useful when you want to wipe test data before launching the real study. Completed responses, in-progress responses, and filter/quota screen-outs are not affected by this button; to wipe those, use the standard Reset counters action on each survey individually (which will also clear the longitudinal screen-outs for that specific survey).

15.6 Deleting a study

Click the × icon next to a study in the listing to delete it. You will be asked to confirm. Deleting a study:

  • Removes the study and all its survey assignments.
  • Does not delete the surveys themselves — they remain intact and become available for other studies.
  • Does not touch any response data — respondent records from each survey are kept as-is.

Only the owner of the study (or a superadministrator) can delete it.