While I’m picking on Brad DeLong, I want to criticize him for something that has nothing to do with economics–the very bad graph that he uses to depict current employment figures.
I think this is a classic example of “how to mislead with graphs.” The decline in employment as depicted here looks massive, running from almost the very top of the graph down to the very bottom. The actual decline is approximately 8.2%,* but occupies over 90% of the vertical space of the chart, implicitly suggesting a decline about 10 times greater than reality.
To be fair, it looks like the real blame for this graph is the St. Louis Fed, but anyone who reproduces it shares in the blame. That’s not to say either the Fed or DeLong are purposely trying to mislead people, but the alternative, simple carelessness, isn’t highly respected, either. Here are some alternative presentations, using the same data.
If, instead of running the vertical axis from just the peak to the trough, we run it for the whole range of (mathematical) possibility, we get a representation that depicts the current downturn in employment as still a distinctly noticeable decline, but not a massive fall-off.
Or we could run the range from 50% to 70%, and get the following image that visually depicts a severe decline, but without suggesting wholesale catastrophe.
That’s the type of graph I recommend to my students. Obviously there’s no objectively correct choice of range to depict, but the choice of the graphmaker matters, and it’s easy to use the figure to try to manipulate the takeaway message. Here are two graphs showing the national debt in relation to the GDP. I like to show these to my students to get them to thinking about how the starting point influences the message. It shouldn’t be too hard to tell which of these is the liberal presentation of the data and which is the conservative presentation.
*From a high of 63.4% to a low of 58.2%.