Diary studies ask participants to record their experiences, thoughts, and behaviours at regular intervals over an extended period, often days or weeks. This longitudinal approach captures how experience changes over time and surfaces the everyday moments that one-off research sessions inevitably miss. Unlike interviews conducted after the fact, diary entries are recorded close to the moment of experience, which dramatically reduces recall bias and captures the texture of daily life with far greater fidelity.
What It Is
In a diary study, participants are given a structured prompt or set of questions to respond to at defined intervals, daily, after specific events, or at moments triggered by their own experience. Responses can be written, photographic, audio-recorded, or a combination. The researcher collects a longitudinal record of experiences across the participant group, which is then analysed for patterns, change over time, and the specific triggers and contexts that shape behaviour. Digital tools have made diary studies easier to run and monitor remotely than ever before.
How to Run It
Begin by deciding on the trigger type: time-based diaries prompt participants at set intervals, while event-based diaries ask participants to record entries whenever a specific type of event occurs. Design a short, consistent set of prompts that participants can respond to in five to ten minutes per entry. Provide a clear briefing document and a practice entry before the study begins. Check in with participants regularly during the study to maintain engagement and answer questions. After collecting entries, code responses by theme and look for temporal patterns, specifically how experience shifts from the beginning to the end of the study period.
When to Use It
Diary studies are particularly well-suited to understanding longitudinal experiences such as onboarding journeys, chronic condition management, learning processes, and the evolving relationship between a user and a product over weeks or months. They are valuable when the research question involves change over time or when the relevant experiences happen sporadically across a person's day in contexts that are difficult to observe directly. They are less appropriate for projects requiring quick turnaround, since even a short diary study typically takes two weeks or more to run and analyse.
Tips for Success
Keep the entry format as simple as possible. Complicated prompts lead to participant fatigue and non-completion. Offer multiple response formats so participants can choose whichever is easiest in the moment. Build in mid-study check-ins to re-engage participants who are beginning to drop off. Treat early entries differently from later ones during analysis: initial entries often reflect what participants think they should say, while later entries tend to be more candid and behaviourally accurate.
