Getting a high participation rate in diary studies

"We will recruit 25 people, because we know that at least 40% drop off during the diary study" is what the Korean consultancy said. I had just run a diary study in the US that uncovered impressive insights, and leadership wanted to see how these insights differed from the Korean market. Unfortunately I do not speak Korean, so I explored consultancies that did. I shared my research proposal, method and insights. But when they looked into it, they were surprised I had a 0% drop-off rate on my diary studies. "HOW did you manage to do that???". The answer is: relationship building (the same answer as making impact at a big company btw).

What are diary studies?

A diary study is a longer study with the same user. Instead of interviewing them once or twice, you could collect their data for a week, month or even a year. You can use different methods within this method, moderated, unmoderated, videos, written, photos, voice messages. You can collect them via fancy services (UserTesting, dscout, Indeemo), or set it up yourself via e-mail, WhatsApp, etc. Basically there are a lot of choices to make when setting up a diary study.

Why would you want a diary study?

To get A LOT of high quality data, but also to observe habits, to observe a change in behaviour, and to study learnability of a program.
If you run research on an e-commerce platform you often do not need longitudinal insights, but if you work on a B2B platform, a word processor that is used regularly, a music provider that is used regularly, etc, it is not only important to see how the product is used in one specific snapshot (often a usability test), but also over time (have users learned anything from the last time they used the system?). You also get way better insights in how the product is used in real life. Your usability test might be run in a lab, but if you work at Voi (those scooters you rent per minute), your users are definitely using your system outside, on the streets, potentially in the rain. Diary studies collect those snapshots.

Why is drop-off rate a problem?

Often you pay your diary study participants, they put quite some time into filling out your forms and they should be rewarded for this. Though, if your diary study is long, participants wonder what they are actually doing, and why they are doing it. Imagine you have to fill out for 14 days in a row how you listened to music, you would start to doubt and wonder what you are doing. So you often over-recruit, to account for the drop-off rate.
But you could also think about a different solution: minimising the drop-off rate.

The solution

The easy solution is of course to cut your reward in pieces and pay out every few days, so the user sees the financial reward.
But, the solution I always go for is to start with an onboarding user interview. Instead of dumping weeks of work on the user, I invite them to a qualitative interview (and the user is aware that there might be a diary study afterwards). This has 2 benefits: 1. I can check if this user really fits my target group and understand if they will add value to the study. 2. We are investing in a relationship. The user gets to know the researcher and understands who they are talking with now, and for the upcoming X weeks. After the interview I invite them to the diary study, and during the study I send motivating comments, follow up questions and interact so they feel that their information is being used.
And that's how I keep my drop-off rate extremely low (with often 100% finishing rate).

Oh and one extra tip if you want to run this yourself, my favourite tool is VideoAsk: both because it helps on the relationship-building with the users, and they can record their answers however they like (video, audio or text).

Want to learn more about diary studies? I talked about the benefits of diary studies at TDC 2025, grab a glass of water (because I am sure you haven't drunk enough yet today), popcorn, and have a listen for the next 20 minutes:

UX beyond the screen: learning from users in real life - TDC 2025

Want to run your own diary study? Or want to run one but do not have time? Send me a message and let's discuss how I can help!