What is Diary study?
A diary study is a longitudinal research method where participants self-report their experiences, behaviors, and thoughts over an extended period, typically days or weeks, using structured prompts.
How it works
Participants record entries at scheduled times (fixed intervals), when triggered by specific events (event-contingent), or both. Modern diary studies use mobile apps, text messages, or email prompts to capture data in the moment, reducing recall bias compared to retrospective interviews. Diary studies excel at capturing behaviors that unfold over time (habit formation, product adoption), vary by context (usage patterns across situations), or are too routine for participants to remember accurately in a single interview. Analysis involves both quantitative patterns and qualitative themes across entries.
Applied example
A fitness app company runs a 4-week diary study where 20 new users record daily entries about when and why they open the app, what they do, and any frustrations. The study reveals that most users stop opening the app after day 8 because the novelty of tracking wears off and no habit loop has formed.
Why it matters
Diary studies capture the longitudinal, contextual reality of user experience that cross-sectional methods miss, revealing how products fit into the rhythm of daily life over time.
