Remaking a great chart

February 12, 2013
By

(This article was originally published at Junk Charts, and syndicated at StatsBlogs.)

One of the best charts depicting our jobs crisis is the one popularized by the Calculated Risk blog (link). This one:

JobLossesJan2013

I think a lot of readers have seen this one. It's a very effective chart.

The designer had to massage the data in order to get this look. The data published by the government typically gives an estimated employment level for each month of each year. The designer needs to find the beginning and ending months of each previous recession. Then the data needs to be broken up into unequal-length segments. A month counter now needs to be set up for each segment, re-setting to zero, for each new recession. All this creates the effect of time-shifting.

And we're not done yet. The vertical axis shows the percentage job losses relative to the peak of the prior cycle! This means that for each recession, he has to look at the prior recession and extract out the peak employment level, which is then used as the base to compute the percentage that is being plotted.

One thing you'll learn quickly from doing this exercise is that this is a task ill-suited for a computer (so-called artificial intelligence)! The human brain together with Excel can do this much faster. I'm not saying you can't create a custom-made application just for the purpose of creating this chart. That can be done and it would run quickly once it's done. But I find it surprising how much work it would be to use standard tools like R to do this.

***

Let me get to my point. While this chart works wonders on a blog, it doesn't work on the printed page. There are too many colors, and it's hard to see which line refers to which recession, especially if the printed page is grayscale. So I asked CR for his data, and re-made the chart like this:

FIGURE 5A-1

You'd immediately notice that I have liberally applied smoothing. I modeled every curve as a V-shaped curve with two linear segments, the left arm showing the average rate of decline leading to the bottom of the recession, while the right arm shows the average rate of growth taking us out of the doldrums. If you look at the original chart carefully, you'd notice that these two arms suffice to represent pretty much every jobs trend... all the other jittering are just noise.

I also chose a small-multiples to separate the curves into groups by decades. When you only have one color, you can't have ten lines plotted on top of one another.

One can extend the 2007 recession line to where it hits the 0% axis, which would really make the point that the jobs crisis is unprecedented and inexplicably not getting any kind of crisis management.

(Meanwhile, New York City calls a crisis with every winter storm... It's baffling.)



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