Understanding how users interact with a product or service over time is essential for building experiences that truly meet their evolving needs. That’s where longitudinal studies come in...
What are longitudinal studies?
Unlike one-off usability tests or surveys, longitudinal studies track user behaviour, attitudes, and experiences across days, weeks, or even months. They generally comprise multiple research methods including surveys, usability testing, diary studies, observational fieldwork, focus groups and one-to-one interviews. Using different methods enables researchers to use the appropriate method at specific times across the customer journey. They also help to triangulate findings in order to have more confidence in the research findings.
When should you use them?
While usability testing is a great way to understand how people interact with a website or app it gives less insight into the overall customer experience. If your customers engage with you and your website multiple times over the course of weeks or months then longitudinal research can be useful for getting a deeper understanding of their behaviours over time.
Longitudinal research is particularly useful for mapping experiences of events with longer lead times, like people booking to attend a festival months in advance. It can also be useful for potentially life-changing experiences, like applying to universities.
What should you consider when running them?
The first question when deciding whether to run a longitudinal study is whether the topic is appropriate. If you run an ecommerce website where people tend to purchase on their first or second visit then usability testing will generally suffice. But if your product or service needs more long-term engagement from users then you should consider running a longitudinal study.
Once you’ve decided that this is the most appropriate way to run your research then you’ll want to consider when and what. There are frameworks that can help you do this and using a model will help you plot when you want to gain insight into the customer journey and what methods are the most appropriate.
The type of method you use will depend on what you want to understand at each stage, and whether you want to take a more quantitative or qualitative approach. For example, surveys will help you to get high-level feedback from large numbers of people, while usability testing will give you more in-depth feedback from a smaller number.
Once you have an outline of your plan, you can complete a research canvas for each of your activities. This will ensure that everything’s on track throughout and that you will be gaining the insight you need at each step.
After you have completed your study you’ll want to bring all of your findings together. This could be on a journey map as well as a series of reports on findings at each stage. As ever, make sure you’re considering the ‘so what?’ at every step. What actions are you recommending based on your research findings?
Summary
Longitudinal studies can be time-intensive, but the depth and richness of insight they offer are well worth the investment, especially when you need to understand long-term user experiences. By planning carefully, choosing the right methods at the right moments, and staying focused on the bigger picture, you can uncover patterns and pain points that short-term research might miss. Whether you're mapping a long decision-making process or tracking engagement over time, longitudinal research is a powerful way to design with greater empathy and evidence.