As product managers, we exist in what I call the “sliver zone”: the tiny space of overlap in a Venn diagram with “user value” on one side and “business impact” on the other. We’re constantly in pursuit of solutions that deliver something meaningful to our users and have a positive impact on our business. We rarely get it right the first time. Or the second. Or the third. 

Product failure — true failure, the kind where, no matter how many A/B tests you run on a solution’s interface or navigation, your users just aren’t into it — doesn’t typically stem from poor interface design. I’d argue that it’s usually the result of forgetting your users are human beings who spend most of their time not using your product. Great product decisions take this into account. One feature that made Pandora successful in its early days was auto-start: when you launch Pandora, music simply starts playing. The insight was that, when users navigated to Pandora, they were doing so because they were experiencing a moment in their lives when they wanted to hear music — not silence combined with a decision to make.

How can product managers get better at understanding users as humans, to find moments in their lives where products naturally fit? Enter the diary study.

A diary study is a type of user research that follows participants for an extended period of time (days, weeks, or even months). Participants log aspects of their day throughout the duration of the study. These can be submitted as written entries, photos, or video or audio files. The point is to understand your users as they exist day-to-day: how they make decisions; what feelings they experience at various moments in their lives; the types of interactions they have, human or otherwise. Because diary studies are self-directed — participants submit their “diary entries” on their own, usually through a digital portal — I find them to be more scalable (and cost-efficient) than a traditional ethnographic study. You can have multiple people participating simultaneously.

We did a diary study during my first few months at Betterment. The team had been making strong, quantitatively rational decisions: decisions that were rooted in product usage data. However, we were missing insights about the purpose our product could have in peoples’ lives. How do Americans — not necessarily Betterment customers, but regular human beings — make decisions about their money? How do they perceive their options for putting money aside? Do they consult anyone in these decisions? Do they feel confident about these decisions, or insecure? These answers would ensure that the solutions we built would augment a user’s financial life — not run parallel to it, or, worse, work against it.

With the help of a research agency, we followed 10 people for four weeks. We asked them to log each time they thought or acted on money during the day. They briefly described these situations, including the emotions they felt and the people involved or impacted. Some participants recorded their responses as videos; non-verbal cues, like tone of voice and body language, gave us a deeper view into the situation. At the end, we had pages upon pages of qualitative information about people’s relationships with money. 

We discovered that we’d been taking for granted the level of confidence people have around their finances. Even the participants with the most diversified savings and investing patterns expressed concern about whether they were “doing it right.” This insight alone was gold, especially for my team. We focus on new customer growth, so meeting a prospective customer where they are — both financially and emotionally — is critical to establishing the trust that ultimately leads to conversion. We now know how to tap into the emotional piece of that equation.

Now, when I’m asked for advice on how to build great products, “run a diary study” is usually one of my first answers, followed by, “remember that your users are human beings who spend far less time in your product than you do.” It’s a way to nudge the “user value” circle of that Venn diagram a little closer to its “business impact” neighbor. 


This article is a contribution by the author and does not reflect the views of Betterment.

About the speaker
Katherine Kornas Betterment, VP of Growth Contributor

Katherine Kornas is VP of Product at Betterment, where she leads growth, mobile, and money movement product teams. Prior to joining Betterment, she was SVP, Product at Havenly, and held product leadership positions at Pandora and Autodesk. Katherine has also worked on product teams at and GreatSchools. Katherine is a graduate of the University of Michigan and currently lives in New York City