It creates more generic-looking interfaces that may perform well in numbers but fall short of appealing to our senses.

It’s easy to make data-driven design decisions, but relying on data alone ignores that some goals are difficult to measure. Data is very useful for incremental, tactical changes, but only if it’s checked and balanced by our instincts and common sense.

It became clear to the team in that moment that we cared about more than just clicks. We had other goals for this design: It needed to set expectations about what happens next, it needed to communicate quality, and we wanted it to build familiarity and trust in our brand.We could have easily measured how many customers clicked one button versus another, and used that data to pick an optimal button. But that approach would have ignored the big picture and other important goals.

Not everything that can be counted counts. Not everything that counts can be counted.Data is good at measuring things that are easy to measure. Some goals are less tangible, but that doesn’t make them less important.While you’re chasing a 2% increase in conversion rate you may be suffering a 10% decrease in brand trustworthiness. You’ve optimized for something that’s objectively measured, at the cost of goals that aren’t so easily codified.

Design instinct is a lot more than innate creative ability and cultural guesswork. It’s your wealth of experience. It’s familiarity with industry standards and best practices.

Overreliance on data to drive design decisions can be just as harmful as ignoring it. Data only tells one kind of story. But your project goals are often more complex than that. Goals can’t always be objectively measured.