Monday, October 31, 2011

visualizing student loan debt

The latest edition of the Economist (Oct 29-Nov 4) includes a short article on US student loans. It describes the increase in student loan debt now vs. ten years ago: aggregate student loan debt is expected to exceed the $1 trillion mark when the next official estimate comes out later this year, surpassing credit card borrowing. The assumption that student loan programs were structured around - that a graduate's future earnings flow will more than cover the costs of a degree - is being called into question given the extended period of unemployment in the current economic environment. The article advocates 1) the changing of bankruptcy laws to forgive student loan debt (they currently do not) and 2) the repricing of student loan debt to either institute mortgage-like repayments (on a fixed schedule) or a movement to income-based payment amounts, with the forgiveness of remaining debt after a given period (e.g. 20 years).

The article includes the following graph. Two questions: 1) Does it fit with the story? 2) What changes would you make? 

It's not a bad graph. It's clean and easy to read. But, like most, there are things about it I'd like to change. If it were my visual, here are the minor modifications I would make:
  • Simplify: remove segmentation. I'm not sure the distinction between public and private student loan debt is interesting or relevant. I'd get rid of the segmentation and just show the overall debt so as not to call undue emphasis to the public vs. private piece. If this is indeed relevant but not high priority, a small footnote could be added to state that "x% of student loan debt is public and the remainder is private" and that the percentage hasn't changed meaningfully over the past 10 years.
  • Simplify: label points directly. The graph is easy to read, but you still have to read it. We could make a couple minor changes to make taking in the information even less work. Rather than have the x-axis across the top, you could remove it and label the bars directly. This would take away the step where you look at the bar and then trace up to the axis to understand the number.
  • Focus attention on the important part. The main point I think the graph is meant to make is how much larger US student loan debt is now vs. ten years ago. Given this, I'd recommend switching the order of the bars so that the 2011 estimate comes first and attracts attention.
  • Cut the clutter. Remove the light blue background (it doesn't add informative value and makes the data stand out a little less) and remove the y-axis line or push it to the background by making it grey.
Here's what the graph looks like when these changes are made (note that I didn't have the underlying data, so estimated the figures visually from the graph provided in the article):

Let's also consider another option. Question: do we need a chart to show this information? One lesson I teach in my class is that when you only have one or a couple of numbers to highlight, often simple text is the best way to do this, because putting the numbers in a graph can cause them to lose some of their umph. Is that the case here? Let's take a look. Here's one way we could visualize the numbers directly vs. in a graph:

I think arguments can be made for either of the above approaches. I do think you get some value from seeing the magnitude of difference with the bars. What approach would you take?


  1. Even though there are only two numbers, which typically are suited just fine with a simple table, for the purpose of this data and the story it's trying to tell, the bars have much more impact and show the true magnitude of the variance.

    I'm with you; there's no need to segment the debt.

    Great blog post!

  2. I think your comments are based on a key mis-assumption: that readers of The Economist are like the general public and want/need highly simplified graphs. I'm going to go out on a limb and say that The Economist must have a much-higher proportion of highly-educated, focused, thoughtful people as an audience, compared to most other publications. They are also more willing to take the time to read read something dense/complex and understand it. With that in mind, I think the editors at The Economist probably made appropriate choices with this graph.

    To start, I'd say the segmentation is interesting information, especially since (from memory) part of the article was about how much the student loan debt burden is supplied from public sources. The chart makes that very clear, although the colors aren't what I would have chosen. Given the inclusion of that extra data, it would be difficult to label the bars directly, so I think they made the right choice with the labels, also.

    I agree, the bigger bar should probably come on top.

    I think the light blue background probably has less to do with the chart itself and more to do with fitting the chart onto the page, and with maintaining page-design standards. I'm guessing, but I'll bet they always put charts on a light background like that, to make them consistent and to separate them from whatever other page elements are around them. I'll bet that's also the reason for the solid Y axis; it's another little detailed clue to help understand the x-axis labels, and probably part of their chart-design standards.

    Net effect: I *totally* agree with your comments in 99% of cases. But in this case, I/we know that this chart came from The Economist, so I don't think they are correct.

    My credentials for saying all this: I'm just a guy, with a background in software development / UI, who cares a bunch about this sort of stuff. My opinion is just that :) I only recently found your blog, but I really like it; thanks! I haven't had a chance to work through the archives, yet, but I plan to do so.

  3. Thanks for the comments! Part of my aim is to create a dialogue and diverse perspectives are welcome.

    Truist: I just reread the article and stand by my opinion that the segmentation of public vs. private debt is unnecessary. It isn't that I think The Economist readers aren't smart enough to read the graph with the inclusion of this segmentation (I applaud anyone who can make it through an entire mag - that's some dense reading!), but rather that the info is irrelevant and thus runs the risk of distracting from the main point.

    It's probable, as you bring up, that the visual details are per The Economist's set design standards. It's true that we must always work within the confines of what our organizations, tools, and audiences will allow. My point was simply that, if I had free reign for design, I would make the changes that I outlined.

    Thanks and keep the comments coming!