A diary study only works if people keep going. The first two days are easy: participants are curious and the tasks are new. By day five the novelty is gone, and the quality of the entries starts to drop. The good news is that most of the reasons people stop are under the researcher's control. Here is what we have seen work.
Start with the time budget
Before writing a single task, decide how much time you are asking for each day. For a study of one to two weeks, five minutes a day is a fair upper limit for most people. For three or four weeks, aim lower. Write the number down and check every task against it.
The usual mistake is to add "just one more question" until each day takes fifteen minutes. People do not drop out because of one long day. They drop out because every day is long.
One task, one job
Each task should have one clear job. "Show us your dinner and tell us how you chose it" is one job. "Show us your dinner, tell us how you chose it, rate your mood, list what you ate today and photograph your fridge" is five.
When a task needs several answers, put the main one first and keep the rest quick: a choice or a rating takes seconds, a video takes minutes.
Pick the right moment
A diary entry is most useful close to the moment. Think about when each task should open:
- At a fixed time: an evening reflection opens at 8 pm in each participant's own time zone.
- On an event: a repeatable "every time you shop" task can be done whenever it happens.
- With a window: decide how long each task stays open. 24 hours is common. A weekend task may stay open longer.
Days counted from each person's own start help too. If someone joins two days late, they still get day 1 first, not day 3.
Remind once, and kindly
Reminders help, but too many feel like nagging. One reminder when a task opens is usually enough. Send it in the channel people actually read: for many participants that is WhatsApp or a text message rather than email. Never send reminders at night, and let people switch them off.
Make the first day easy
Day 1 teaches people how the study works. Use it for a short, friendly task, such as "Introduce yourself in 30 seconds and show us where you are". It checks that recording and uploading work, and it gives you a face to remember for each code.
Show people they are heard
The strongest motivator in a diary study is a reply. A short follow-up question on day three about something said on day one tells the participant that a person is watching. Keep follow-ups specific: "You said the app was confusing on Monday. What happened exactly?"
Watch the dashboard for people who go quiet, and write to them early. A friendly message after one missed day works better than a warning after three.
Vary the format, not the core
If you want to compare days, keep one core question the same every day, in the same format. Around it, vary the rest: a photo one day, a voice note the next, a short video on the weekend. Variety keeps people interested without breaking your comparison.
End well
The last task should feel like an ending: "Looking back over the two weeks, what changed?" Then thank people properly. A thank-you message when they send their last task, and a clear word on incentives, leaves a good feeling and makes people more willing to take part again.
A sample two-week plan
- Day 1: introduce yourself (video, 30 seconds) and a photo of where the product is kept.
- Days 2 to 13: each evening, a one-minute video on today's use and a mood rating. A repeatable "every time you use it" task for quick notes.
- Day 7: a short tour video, "Show us how you use it now, compared with day 1".
- Day 14: the look back, a final rating, and the thank-you.
Checklist
- Daily time budget written down and respected
- One job per task, with quick questions after the main one
- Tasks open at a sensible time in each participant's time zone
- One reminder per task, in the right channel, never at night
- A light first task
- Follow-ups from day two or three
- The same core question every day if you want to compare
- A real ending and a thank-you
On Zolensa, tasks open by day in each participant's time zone, reminders go out once by email, WhatsApp or text message, and the dashboard shows who needs a nudge. See the diary studies use case for details.
