Diary studies and the potential to capture decisions as they happen

As an online grocery store we often wonder what drives behavior at the moment of decision. What makes you add things spontaneously to the cart? How do you know it's time to go to checkout? We can of course ask customers in interviews or surveys, but this relies on people remembering what happened and that they were aware of their own reasons in the moment of decision. In a recent study we tried to tackle this by following 20 customers over 6 weeks, and have them make a short video diary each time they shopped groceries. In this talk we want to share what made the diary study work (we all had some earlier faulty diary attempts behind us), and what we wish we had known ahead of this project.