February 18, 2014
Cork Gaines of Chart of the Day has once again provided me with a terrible chart to pick apart. The idea behind this chart is simple, but the execution is nothing short of terrible. Let's start with the chart Cork produced:
I like Cork's idea: How did the Seahawks defense rank against the best defenses of all-time? His primary method of measurement is how each team compared to the NFL average. Makes sense.
However, there is way too much going on in this chart to make any sense of it.
- Cork chose to show two measures. This confused me. Do all of the teams make up the top 15 in each of these categories? I doubt it. It turns out that the measure he's ranking them on is PPG allowed vs. the NFL average. So why include YPG allowed?
- Why show 15 teams? Showing the top 10 makes it easier to find where the Seahawks rank.
- The point of the article is to highlight the Seahawks, yet he fails to highlight them. You have to do too much work to find them.
- The teams are ranked in reverse order. For some reason, nearly every chart that Chart of the Day produces is sorted backwards. I suspect they’re using Excel to create their charts. The best team should be on the left, not the right. If you don't pick up on that, you might be led to believe that the 2005 Bears had the best defense, when in fact it's the 1975 Rams (who are way over on the right).
- He's barely highlighting the teams that won the Super Bowl with a tiny asterisk.
- The chart forces you to turn your head 90 degrees to the right to read the labels.
- Is the axis needed? All of the bars are labeled, so I would say no.
I'm sure there are some other things I'm missing, but I'm too irritated with this chart to continue to make myself suffer.
Since I'm in the process of testing Tableau for Mac, I decided to build my version of the chart there.
How did I address my concerns with Cork's chart?
- I decided to only show PPG allowed vs. the NFL average. I wanted to keep it simple.
- I’m only showing the top 10 teams.
- The point of the article is to highlight the Seahawks, which I've clearly done.
- The teams are ranked in the correct order, starting with the best defense on the left.
- I decided to highlight the Super Bowl winning teams by showing the Lombardi Trophy. This makes it easier to see that having a great defense does not guarantee the title.
- I've made the team names much easier to read by displaying the text horizontally.
- The bars are labeled and they all start at zero, so I've eliminated the axis.
It saddens me to see the consistently poor output from Chart of the Day. They have so much interesting sports data to work with, yet they continue to communicate their stories so, so poorly. Maybe I should send Cork a copy of Data Visualization: A Successful Design Process by Andy Kirk and/or Show Me the Numbers by Stephen Few.
February 3, 2014
When I was in Israel last week, we wanted to create a visualization that included band lines based on confidence intervals in the database. In other words, our table contained two measures: value and confidence interval.
Allen Smithee had created some interesting looking Bollinger Bands before, so I started there. I downloaded the workbook and noticed that while these look decent, they’re not perfect. This is the initial view:
Looks pretty good. But when you remove the lines for the upper and lower bands (or if you zoom in), you will see that the bands were made via reference bands for each discrete date, which makes them look like bars. I suspect the lines for the upper and lower were included to hide the rough edges of the bars.
Here’s how he created the reference lines:
I don’t think this looks polished enough, so I took an alternative approach: area charts.