Sure, marketing or user data has almost always been used to influence and guide web design to some degree, but what does data-driven design mean for us today? The answer to that question requires taking a good look at what data is. Most data is either quantitative (numerical) or qualitative (non-numerical). And the vast majority of easily-accessible data is quantitative. For example, Google Analytics informing you that 10 visitors viewed one blog page, while 1 visitor stopped by another.
Qualitative data is important. Following the numbers can help you find what visitors value and what they do. But it doesn’t tell you why they like it. And understanding that requires qualitative data. The best web design companies are pushing the field by getting qualitative data and modifying their designs based on this data. They’re using beta-testing systems and getting powerful, direct feedback.1
A good data-driven design program will always use both kinds of data. Testing, analysis, and feedback systems are continuous, rather than one-off, and therefore provide deeper insights on what visitors prefer and want the websites they visit to do for them. It is this kind of deep-digging which pushes the horizon of design forward in ways which are meaningful for users.