Diary Studies
Participants record their own experience over time, which captures things a single session cannot.
Definition
A diary study has participants log activities, thoughts or problems over days or weeks. It captures infrequent events, changes over time and the natural rhythm of use.
Established research. Originates in published research and has been replicated. The effect is real. Its size in your product still needs measuring.
On this plate
Reach for this when
- Behaviour unfolds over days or weeks.
- Events are too infrequent to observe directly.
- Understanding onboarding or habit formation.
- The behaviour is spread over weeks, or happens in places you cannot observe.
Common mistakes
- Entry burden that causes dropout.
- Fixed-time prompts that miss the moment.
- No mid-study contact.
- Recruiting people who are unusually organised, who are the ones most likely to volunteer for a diary.
Running one
- Keep each entry under two minutes, or compliance collapses by the third day.
- Prompt at the right moment: triggered by an event where possible rather than at a fixed time.
- Allow the format participants find easiest: voice notes, photos, short text.
- Check in during the study, not only at the end.
- Follow up with interviews to explore what the entries show.
- Budget for attrition. Expect to lose a meaningful share of participants.
Keeping participants in
Do
- Keep each entry under two minutes, and accept a photograph or a voice note as an entry.
- Prompt at the moment the behaviour happens, not at the end of the day.
- Check in personally in the first two days, when most dropout happens.
- Pay for the whole study, and say so up front.
Do not
- Ask for a daily long-form reflection. You will get three days of prose and then silence.
- Leave the study running longer than the behaviour you are studying needs.
- Treat the entries as the finding. They are the raw material for the closing interview.
In practice
- i.
Catching the infrequent case
What it is forA monthly reconciliation task is almost impossible to observe and easy to misremember. Two months of short entries produced the sequence, the interruptions and the workaround that no interview had surfaced.
Local chart
RES·013 · Region IV · Grid G1
This entry and the entries it is stated to connect with. Each line is labelled with what the connection means.
Sources
Where a source establishes something narrower than the popular reading of it, the note says so.
- [1]
Universal Methods of Design
B. Martin and B. Hanington, Rockport, 2012
Method summaries, including diary and experience sampling variants and what each one costs a participant.
Continue from here
Each link says what the connection is, so you can tell a principle from an alternative from a thing people mix this up with.
Applies when you are designing
Principles behind this
The reasoning this solution is an application of.
- Spacing EffectPSY·008 · Psychology
Short definition
The one-paragraph version, for when that is all you need.
- Longitudinal StudyTERM·030 · Term
Related concept
Connected closely enough to change how you apply this.
- Research Notes to InsightsAI·003 · AI workflow
- OnboardingPAT·014 · Pattern
- Affinity MappingRES·020 · Research method
- Contextual InquiryRES·012 · Research method
- Research SynthesisRES·014 · Research method
- User InterviewsRES·003 · Research method