01 / UNDERSTAND
What is a diary study?
A diary study asks participants to record relevant experiences across a period of time. Entries can use short text, audio, photographs or another accessible format. The method brings repeated events and changing circumstances into view when one interview or observation would miss them.
The record is participant reported. It captures what someone noticed and chose to record, not an uninterrupted view of everything that happened.
Why use Diary Study?
A service can work on an ordinary day and become difficult when circumstances change. Diaries help designers follow those changes without continuously observing people. They also provide concrete episodes to discuss later, reducing reliance on a single retrospective summary.
When to use it
USE IT WHEN
An experience unfolds over days or weeks.
Relevant events happen unpredictably outside a research session.
You need to understand variation within the same person’s circumstances.
When to choose another method
Use User Interviews for a focused account of a recent event when repeated recording adds little.
Use Contextual Inquiry when you need to observe details people may not notice themselves.
Use service analytics for frequency estimates when reliable instrumentation and coverage exist.
What you’ll need
Define the events of interest, a realistic duration and the decisions the study should inform. Recruit people with relevant experience and varied circumstances. Agree recording choices, consent, privacy, support and compensation. Pilot the prompts and burden before launching. Avoid asking participants to capture identifiable information about other people.
What the method needs
Keep the elements that help answer your question and support a decision.
The experience or change the study should help explain.
An event, interval or combination that tells participants when to respond.
A short request for context, action and outcome.
Reminders and assistance that do not turn into coaching.
Links between entries, follow up accounts and uncertainty.
02 / PUT IT INTO PRACTICE
How to run a diary study
Keep evidence and assumptions distinct. Revisit your work when new information changes your understanding.
01
Define the time window
Choose a period likely to include the experience and meaningful variation. Explain why that period fits the question.
A study of weekly meal planning should include planning and the days that follow.
02
Design a small entry
Ask only what is needed to understand an episode. Allow a brief entry rather than requiring an essay.
What changed, what did you do, and what happened next?
03
Pilot with realistic constraints
Check comprehension, accessibility and how long recording takes. Adjust the task before treating missing entries as participant failure.
Try making an entry during a busy moment.
04
Start and support the study
Demonstrate an entry without prescribing its content. Agree when reminders will arrive and how people can pause.
Keep a record of researcher contact that may influence responses.
05
Review while the study runs
Check for technical problems and unclear entries. Ask neutral clarification without rewarding particular kinds of story.
Do not remind someone specifically to report frustrations.
06
Interpret episodes and changes
Compare situations within each diary before comparing people. Follow up on gaps and unexpected contrasts.
Separate no relevant event from an event that was not recorded.
07
Connect learning to a decision
Identify a design implication and the evidence still needed. Preserve episode references so colleagues can inspect the reasoning.
A recurring disruption may suggest a recovery feature worth prototyping.
Example: when meal plans change
Fictional study scenario: a team explores how people adapt a weekly meal plan. Participants would record moments when the plan changes, using a short voice or text entry. The proposed prompt asks what changed, what they did and what made the choice possible.
An invented entry describes arriving home late and using frozen food; another describes sharing an unexpected meal with a neighbour. Both depart from the plan, but only one might involve unwanted effort.
The team would examine whether its product should support adaptation rather than simply encourage compliance. A blank day cannot establish that the plan worked. A follow up conversation would clarify whether nothing changed, recording was inconvenient or the participant paused.
03 / BELOW THE SURFACE
Below the surface: missing entries have a shape
The situations most important to understand may also be the hardest moments to document.
GAP
What is missing from this record?
Distinguish missing reporting from absence of an event.
CONDITION
When was recording difficult?
Investigate burden without assigning blame.
CLAIM
What can we still conclude?
State the limits alongside the pattern.
A busy evening may generate both a disrupted meal and a missed diary entry. If the team reads only completed entries, it could overrepresent calm, manageable situations. Treat recording conditions as part of the evidence.
Keep missed prompts, late entries and support contacts visible without assuming a reason for them. Ask participants about the recording experience during the closing interview. Compare immediate and retrospective entries cautiously because they were produced under different conditions.
This editorial check does not recover missing events. It helps the team make a narrower, more defensible claim and improve the next study’s design.
Diary Study companion worksheet
Page one plans the study and records a reusable entry prompt. Page two follows an episode from participant account to interpretation, missing context and a possible design decision. Duplicate the entry record for additional episodes.
Practical tips
Offer an accessible recording format participants can sustain.
Review within each person’s context before aggregating themes.
Common mistakes
Requesting more detail than the question needs.
Assuming silence means nothing happened.
Turning diary entries into unsupported prevalence estimates.
What you’ll get
A set of contextual episodes showing how an experience changes over time, plus questions for follow up. Use the patterns to guide design exploration while retaining the limits of self reporting.