Diary Method — Research Diary Method
Research Diary Method · Also known as: diary study, diary technique, self-report diary, daily diary method
The diary method is a data-collection technique in which participants record their thoughts, behaviours, events, or experiences in their own words at regular or event-contingent intervals over a defined study period. By capturing data close in time to the event, diaries reduce retrospective recall bias and give researchers access to the texture of everyday life as it unfolds — something one-off surveys and retrospective interviews cannot provide.
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When to use it
Use the diary method when your research question concerns within-person change, variation, or experience over time — and when proximity to the event matters (e.g., mood fluctuation, daily stress, health behaviour, relational dynamics). It is also well-suited when retrospective recall would introduce systematic distortion, such as research on eating behaviour, pain, or interpersonal conflict. Do not use diaries when: (a) the phenomenon is rare enough that participants may go days or weeks without a recordable event; (b) the population cannot sustain the burden of repeated entries (e.g., severe cognitive impairment); (c) the research question calls for a single cross-sectional snapshot rather than temporal process; or (d) tight experimental control over stimulus presentation is required.
Strengths & limitations
- Captures naturally occurring behaviour and experience in context, close in time to the event, sharply reducing retrospective recall bias.
- Enables within-person analysis, revealing how the same individual varies across days or situations — a level of granularity impossible with single-occasion surveys.
- Flexible format: open narrative entries suit qualitative questions; structured rating scales suit quantitative or mixed designs.
- Participants become active recorders of their own lives, which can itself increase engagement and reflective awareness.
- Suitable for longitudinal research without requiring repeated lab or clinic visits, making large geographically dispersed samples feasible.
- Compliance degrades over time; longer study periods see higher rates of missing entries, selective dropout, or retrospective filling-in.
- Reactivity: the act of diary-keeping can change the very behaviours or thoughts being recorded, introducing a measurement artefact.
- Open narrative diaries produce large volumes of text that are time-intensive to code and analyse.
- Participants must be able and willing to record entries consistently — populations with low literacy, high time pressure, or limited digital access present practical barriers.
Frequently asked
How long should the diary study period be?
There is no universal rule; the period should be long enough to capture meaningful within-person variation but short enough to sustain compliance. Most published studies run between one and four weeks. Studies shorter than three days risk missing the phenomenon of interest; studies beyond two months see sharp attrition unless entries are very brief and participants are highly motivated.
How many participants do I need?
Sample size depends on the analytic goal. For qualitative thematic analysis, 10–20 participants generating rich narrative entries is often sufficient to reach saturation. For multilevel modelling of quantitative data, at least 30–50 participants and 10–20 occasions per person are common minimum recommendations, though power depends heavily on the expected effect size and the intraclass correlation.
What is the difference between a diary method and experience sampling (ESM)?
Experience sampling method (ESM) is a specific variant that uses randomly timed signal-contingent prompts — typically multiple times per day — to capture momentary states with minimal memory bias. The diary method is a broader family that includes interval-contingent (end-of-day) and event-contingent designs at lower frequency, and often accommodates narrative as well as structured data. ESM is the stronger design for momentary states; diaries are more practical for daily summaries or less frequent events.
Can diary data be analysed quantitatively?
Yes. When diary entries include structured rating scales or counts, the resulting multilevel data (occasions nested within persons) are typically analysed with multilevel modelling (HLM / mixed-effects models), which partitions variance into within-person and between-person components. This allows researchers to ask both how people differ on average and how the same person varies across situations.
How do I minimise reactivity?
Full elimination is rarely possible, but reactivity can be reduced by: using shorter, less obtrusive entry formats; framing entries as simple records rather than self-improvement exercises; including a brief run-in period whose data are excluded from analysis to allow initial reactivity to diminish; and measuring reactivity directly by including a reactivity check item.
Sources
- Alaszewski, A. (2006). Using Diaries for Social Research. Sage. ISBN: 978-0761941415
- Bolger, N., Davis, A., & Rafaeli, E. (2003). Diary methods: Capturing life as it is lived. Annual Review of Psychology, 54(1), 579–616. DOI: 10.1146/annurev.psych.54.101601.145030 ↗
How to cite this page
ScholarGate. (2026, June 3). Research Diary Method. ScholarGate. https://scholargate.app/en/survey-methodology/diary-method
Which method?
Set this method beside its closest kin and read them side by side — the library lays the books on the table; the choice is yours.
- Field NotesSurvey Methodology↔ compare
- Longitudinal SurveySurvey Methodology↔ compare
- Non-participant ObservationSurvey Methodology↔ compare
- Participant ObservationQualitative Research↔ compare
- Semi-Structured InterviewQualitative↔ compare