Charts: The Good, the Bad and the Ugly

bar_chartFor those in the economics profession, it is not unusual to hear a phrase like, “Hey, that’s a nice chart!” Recently, I stuck a simple chart that illustrated GDP into a PowerPoint slide, and it was described as “ugly.” In this world, communication is almost synonymous with a set of charts. And thanks in part to our image-filled Facebook, Pinterest, and Twitter feeds, all forms of communication are evolving into the art of designing images to tell a thousand words.

Justin Wolfers, a well-known economist, recently blogged about the power of charts in a hilarious posting, “A Persuasive Chart Showing How Persuasive Charts Are.” He provides an example from two Cornell researchers, Brian Wansink and Aner Tal, who studied participants’ reactions to pharmaceutical data presented in two different formats. First, the group simply read the results that were written out, and then a subset of the group was shown the same data in a chart form. Translating the description into a chart increased the proportion of people who believed in the drug’s efficacy from, 68 to 97 percent. The study concludes that among the participants who agreed with the statement, “I believe in science,” there was a lot more credence given to data that was presented in a chart versus simply through prose.

I suppose the simple take-away of this story could be the importance of nice charts. However, it also seems to highlight the increasing need to scrutinize charts and the relationship of data sets. There is something about a set of bars on a chart that makes the mind want to look for patterns. These patterns do not necessarily indicate any significant relationship among the data being shown.  If I charted out the time my neighbor ate dinner and the time I woke up in the morning, the chart would probably look nice. However, it would falsely indicate to a reader that there was an important relationship between these two nuggets of information, which there is not. So, we can all come across a “nice chart,” but let’s make sure that we are being critical of the sources and the relationship of the data before we arrive at any conclusions.

Do you think we are preparing our students to do this in our world of Pinterest and Facebook? Are there strong enough, well-understood conventions on data presentation incorporated into our curriculums? Share some of the off-the-wall charts you have come across….

College Football Season and Mathematics

By Cindy Ivanac-Lillig

The start of every new college football season always holds so much promise. My undergrad alma mater, Boston College, is usually good but just not good enough to stick it out in the top ten for more than a couple of weeks — that’s in a good year. This week, the Wall Street Journal published a graph of college football teams, where the x-axis represents the strength of the team as measured by on-field performance and the y-axis represents a measure of ethical behavior (from embarrassing to admirable). It is really neat, albeit somewhat disappointing that BC is marked as highly admirable ethically and a weakling competitively. But, remember, anything is possible.

So, you are wondering what does this have to do with economics or economic education. Behind all the tongue and cheek analyses, there is an impressive amount of mathematics behind this graph that I think many students would find interesting. How about if we asked students to create the mathematical equation that would plot these teams on the graph? All of a sudden the concept of data analysis would seem like lunch conversation and scrutinizing data sources would seem necessary. I am not suggesting that sports statistics hold the answer to classroom mathematics, because first and foremost, these interests would skew male, but just that statistics and mathematical analyses can be applied to a lot of things that are interesting. Please post any and all ideas you might have for the community as to how to bring interesting math problems back to the classroom.

And for now, here’s to hoping that the equation they used to plot my alma mater is flawed. Go Eagles! And to support all my big and little fans at home, Go Irish!

A blog designed to act as a resource and sounding board for promoting economic education.