We know some things about data visualization, and we don’t know others. But it turns out that many of the things we think we know, we actually don’t. Much of what we believe about charts and visualization is based less on evidence and well-constructed science than we like to believe. Are bar charts always the best choice? Are embellishments bad? Are pie charts really evil? Is animation always distracting? When might it work?

Instead of well-run experiments and real evidence, many supposed rules are based on opinion, aesthetic judgments, and incomplete or oversimplified studies. You wouldn’t know that from the level of conviction with which these things are often stated. In this talk, I will show you that some of the things we just assume to be true are actually wrong. There are many things we don’t really know—and it is important to ask, how do we know that?

Robert Kosara is a research scientist at Tableau Software. His focus is on the communication of data through visualization and visual storytelling. Robert received his M.Sc. and Ph.D. Degrees in Computer Science from Vienna University of Technology (Austria). His blog, eagereyes.org, is a popular resource on information design.