UX Glossary · D
Diary study
Also: Experience sampling
Asking participants to record their own experiences over days or weeks, capturing what a single session cannot.
A diary study asks participants to log their experiences over time, in their own words, as things happen. Entries might be prompted at intervals, triggered by an event, or left to the participant’s judgement.
The method comes from psychology, where experience sampling was used to capture behaviour in the moment rather than through recall.
What it catches
Anything that unfolds over time. Habits forming or failing to form. The second-week drop where novelty wears off. Problems that only appear at month end. Occasional tasks that no usability session would ever schedule.
It also avoids recall bias. Asked in an interview how often something annoys them, people guess badly. Logged in the moment, the frequency is closer to true.
The main constraint
Participation decays. Diary studies are work for the participant, and compliance falls over the study period. The countermeasures are practical: keep each entry very short, prompt at sensible times, make submission possible from a phone in under a minute, and pay properly.
In practice
Two weeks is a common length. Pairing a diary study with interviews at the start and end works well: the interviews give context and let you ask about patterns the diary revealed.