Same Data, Different Graphs (aka “Lies, Damned Lies, and Statistics”)
Here are two graphs done early this year, regarding U.S. job losses resulting from the current financial recession, as compared to previous recessions. Both graphs use the same data, from the Bureau of Labor Statistics, but the difference between the graphs is startling. The first graph was put out by the office of a politician, Nancy Pelosi. The second graph was put out by a journalist, Fielding Cage, at TIME magazine.
This could have come straight out of a book by Edward Tufte, or any of those various classics about lying with statistics.
This feat of manipulation was accomplished using three tricks:
1) Vertical scaling: Both graphs use a y-axis that is proportionately bigger than the x-axis, but Pelosi’s does so a bit more, thereby exaggerating the downward slope of recent job losses.
2) Absolute values: Pelosi’s graph counts actual number of jobs lost, instead of the percentage of jobs lost. The workforce has grown considerably over the years, so once again, this exaggerates the downward slope of recent job losses.
3) Narrower context: Pelosi’s graph uses fewer past recessions in the comparison, and leaves out the more-severe 1981 recession, as well as two shorter-lived recessions ( 1974 and 1980). This substantially reduces the nuance in our mental comparison with past recessions, and skews our extrapolation of what might happen going forward with the current recession.
This would be an insult to our intelligence, if it wasn’t such a perfect example for instructional purposes… a fine example of information design. On a practical/political front: Score three points for cultivating greater hysteria on the one hand, and cynicism about data & public policy on the other hand.
The only thing lamer than this? This graph :
This bit of USA Today-worthy Chart Junk put out by the Republican party (and posted to their website) tracks how many jobs were lost since Democratic Party took control of Congress in 2007… which compares nothing with… well… nothing. It’s like some sort of weird Creationist theory of economic history that picks an arbitrary “Day One” and denies the existence of independent natural forces, forces that can’t be fully controlled by the would-be gods in Washington. If this were a tongue-in-cheek reprise to Pelosi’s graph, it might be clever, but it’s not… it’s just upping the ante of stupidity. Memo to both parties: Get Real.
Context and perspective is everything, ain’t it?
(More graphs and analysis on the above can be found on William Poley’s blog.)