In-person qualitative research has natural quantity limitations—there are only so many individuals you can talk to in a given amount of time. But with remote research methods like digital diary studies, the rules suddenly seem to change. It’s less strain on your budget. You’re no longer bound to a single location. And the time! When you eliminate in-person logistics, it seems like you have an abundance of time to spend analyzing more inputs.

But should the rules change?

We don’t think so...or not entirely at least. The old saying that more is not always better applies to diary studies too.

It’s easy to forget that diary studies are still a qualitative, individual-focused method (at least how we see and plan them). We believe you should talk to more people through a diary study than you would in a day of qualitative interviews.

But how many more?

About 5-15. Yup, you heard us right.

We’ve found that between 5-15 participants meets most research needs. Of course, this varies on what you’re trying to learn and how involved the study is going to be. Regardless of how many participants you ultimately decide is right for your study, we believe a single designer or researcher should never manage more than 15 participants at a time.

Think of it like a dinner party: how many guests can you keep track of, talk to, and make sure they’re well taken care of? We bet that for most of you, that number probably tops out around a dozen.

We even drew up a quick post-it to compare where a digital diary study sits alongside a few other research methods when it comes to number of participants:

Where a diary study sits versus other research methods

What if you MUST talk to more people? (We know, it happens.) In that case, divide those individuals into groups of 10-15 and assign a single person to manage each group.

For digital diary studies like obvi text, you’ll be interacting more frequently with participants than you would in a physical diary study. Just consider how much more frequently you text someone than you send them actual mail. The same goes for digital diary studies.

More on that later. In the meantime, just remember: a good diary study is one where every participant feels cared for and attended to. Go with more than you could in one-on-one interviews. But not too many more. Somewhere between 5-15 is probably just about right.