What is a diary study?

A diary study is a qualitative research method that asks participants to record their own experiences, thoughts, or behaviors at set intervals over days, weeks, or months.

Instead of asking someone to recall a purchase, a support call, or a first week on the job after the fact, a diary study captures those moments close to when they happen, in the participant's own words.

Market researchers, customer experience (CX) teams, and HR professionals all use diary studies, not just UX researchers. Anyone trying to understand behavior and emotion as they unfold, rather than at a single point of contact, is a candidate for this method.

Diary entries can take several forms:

What separates a diary study from a one-time survey or interview is repetition. Participants respond multiple times across a set period, which builds a timeline of real, in-context data instead of a single snapshot pieced together from memory.

Diary studies fall under the broader umbrella of longitudinal research, since they track the same participants over time.

This article stays focused on the diary method specifically: what it is, when to use it, and how it differs from other qualitative approaches.

If you want a full breakdown of longitudinal designs like panel, cohort, and retrospective studies, see our longitudinal study guide.

A diary study earns its place on the research plan when you need to understand a process that unfolds over time, rather than a single decision or interaction. It's the right tool when:

Most diary studies run anywhere from one to six weeks. The right length depends on how often the behavior you're studying happens naturally.

A study on daily habits, like meal planning or medication use, might only need one to two weeks of entries.

A study on a slower process, like onboarding a new employee or adopting a new tool, often needs four to eight weeks to capture real change.

Because diary studies produce many entries per person, most research teams work with eight to 20 participants.

Fewer than eight makes it hard to spot patterns across people. More than 20 often produces more entries than a team can realistically read and code, especially over a multi-week study.

Diary studies aren't only a UX research tool, even though that's where the method is best documented.

A field study sends a researcher out to observe participants in their own environment, usually across a single visit or a short series of visits.

A diary study instead asks participants to observe and report on themselves, without a researcher present, across far more touchpoints than a team could realistically visit in person.

A field study shows you the environment. A diary study shows you the pattern over time.

A one-time interview relies on a participant's memory of what happened days, weeks, or months earlier. Memory fades and reshapes itself, especially for routine or emotionally minor moments.

A diary study captures the experience close to when it happens, so entries carry less hindsight bias than a recalled account.

Interviews are still valuable for exploring the why behind a pattern. Many research plans pair a diary study with a follow-up interview once the entries are in, to ask participants about details that stood out in what they wrote.

A few related terms come up alongside diary studies. Here's how each one is different:

You don't need a dedicated diary-study platform to run one.

Repeatable, mobile-friendly survey collection methods sent to participants on a schedule can capture the same kind of daily or weekly entries that a specialized research tool would, without the extra cost and setup.

For teams outside UX research, including market research, CX, and HR, that accessibility often makes the difference between running a diary study and skipping the method altogether.

A team studying how households plan weekly meals sends a short mobile survey to 15 parents every evening for three weeks.

Each entry takes about two minutes and asks what they served, what influenced that choice, and whether a recipe, an ad, or someone else's suggestion played a role.

After three weeks, the team has more than 300 entries showing which influences show up on a Tuesday that never show up on a Sunday, a pattern a single interview would not surface.

A CX team wants to know how a customer's frustration with a shipping delay changes across a week, not just how they feel the moment they file a complaint.

They send a brief survey by email each day for five days after a complaint is logged, asking customers to rate their current frustration and describe what changed since the last entry.

The pattern across entries shows whether the fix resolved the feeling, not just the ticket.

An HR team wants to understand what actually trips up new hires in their first month, beyond what shows up in a single 30-day check-in survey.

New employees get a short mobile form once a week for six weeks, with prompts like "What question did you have to ask more than once this week?" and "What made this week easier or harder than the last one?"

The weekly entries reveal exactly when confusion peaks, information a single retrospective survey tends to smooth over.

A diary study fills the gap between a single-point survey and a full ethnographic project.

It works because it catches people while the experience is still fresh, and that's exactly why it belongs in more toolkits than just UX research.

A market research team tracking a purchase journey, a CX team watching sentiment shift after a fix, and an HR team following a new hire's first month are all asking the same underlying question a diary study is built to answer: what does this look like over time, not just right now?

You don't need specialized software to start. A recurring, mobile-friendly survey sent to the same group of participants on a set schedule can capture daily or weekly entries just as well as a purpose-built research tool.

Ready to try it? Explore SurveyMonkey survey templates to build your first diary study prompt in minutes.