I missed the Twitter exchange about radar plots yesterday.
— Luke Bornn (@LukeBornn) May 17, 2017
I caught up with some of the exchanges through a Ted Knutson post about Revisiting Radars.
Ted noted “The fact that lots of people have reactions to this type of work is a good thing, not a bad one”.
I have been using radar plots in my work for some time. I am mindful of the issues that Luke and Sam (@stat-sam) raise.
Some time ago (2008), I was fascinated by the title of a Purna Duggirala (Chandoo) post You are NOT spider man, so why do you use radar charts? I enjoyed Graham Odd’s (2011) critique of radar charts too.
Primed with Graham’s observation:
… the overall shape presented for a series on a radar chart does not leverage any of the pre-attentive attributes we perceive quantitatively. In essence, this means we are unable to attribute much genuine meaning to the shape of a series. The only patterns our visual perception can really discern in a data set presented as a radar chart are similarity and extreme outliers.
I tried to use my radar charts as a stimulus for conversation. Like, Ted, over the years I have found radar charts a good way to hook attention and trigger conversation. I had similar experiences to Ted in a variety of sport contexts:
In situations like this, visuals go a long way toward opening the conversation. If you show a table of numbers to a coach who isn’t already on board, you’re dead. Bar charts? Only mostly dead. Radars? Interesting… Tell me more.
My use of the charts acknowledged the limitations of the visualisation. Once the coaches had started to discuss the issues raised by a fallible (flawed) visualisation, we inevitably started to discuss how performance might be re-presented (represented) which led in many cases to some fascinating second-order conversations about observation and the narratives we build around performance … and other forms of visualisation.
My willingness to use radar charts dates back to William Anderson’s (1971) discussion of descriptive-analytic research in physical education. He notes:
Their principal concern is to collect accurate descriptive records of events in actual classrooms and to analyze these records in a way that enables a better understanding of the events. (1971:2)
The descriptive records of teaching which emerge are in many ways like the descriptive record of a basketball game contained in a basketball shooting chart. The shooting chart is a diagram of a basketball court on which is recorded the number of each player who took a shot, the place on the court from which the shot was taken, and whether the shot was made. The shooting chart is a record of a critical dimension of “real world events” (the game). A careful examination of the chart can lead to understandings and insights which were not possible during the game itself. In much the same way, descriptive records of teaching provide a picture of real world events (classroom interaction) which lead to a deeper understanding of the teaching process. (1971:3)
Ted makes the point “As I designed them, radars exist to help you open the door with statistical novices, and from that perspective they have been wildly successful”.
This happened in conversations about pedagogy too in William Anderson’s work.
Like Ted, I am acutely aware of the flaws in radar charts. We have unprecedented expertise in sport now. The stories we can produce have immense visualisation resources to share performances. The key for me will be how we work with a variety of audiences in sport, and particularly in decision support for coaches, to achieve the level of engagement Ted reports:
Radars start a conversation. They get a reaction. And for whatever reason, football people are often more comfortable talking about and digesting them than almost any other vis type I have encountered. (Original emphasis.)
These issues are why I have included Audiences and Messages in my open, online discussion of sport informatics and analytics. We have great opportunities for conversation in our community of practice about diverse practices.