There's an old joke in math circles about Richard Nixon that goes like this:
"In the fall of 1972, President Nixon announced that the rate of increase of inflation was decreasing. This was the first time a sitting president used the third derivative to advance his case for reelection."
(A derivative, one recalls, is a rate of change of a value.Nixon was saying that the rising price of goods and servicesinflation, our first derivativewas itself risingsecond derivativebut that the rate at which it was increasing was on the declinethird derivative.)
Historians () trace this observation to theof the "Notices of the American Mathematical Society," in which editor Hugo Rossi wondered if voters fell for it:
"Was President Nixon telling us that the economy was getting better? Did his listeners understand that in fact the inflation rate was still increasing and thus the economy still worsening?"
When it comes to economic data, there is almost always a time frame and a measure of calculus that can make the news sound good. The 2012 election arguably hinged on whether voters saw the economy in gross termshow many total jobs were being createdor as a rate of changehow quickly the economy was improving. In the , President Barack Obama emphasized the former: "Over the last 30 months, we've seen 5 million jobs in the private sector created. "By the , Republican nominee Mitt Romney was mournfully trumpeting the latter: "You can't have an economy that over the last three years keeps slowing down its growth rate." (That's a second derivative, for those of you keeping score at home.)
This is not your basic "lies, damn lies, statistics" situation. It's a foundational question about how far back our memories go when judging the health of the economy, and how far forward our imaginations go when projecting current trends.
Last week, the Census released anon the number of people employed in over 1,500 industries in 2011. This dataset, called "County Business Patterns," is an annual survey of just about every sector of the U.S. economy, with the notable .
The absolute figures in this sort of data can be hard to make sense of if, like me, you are not an economist. Is the fact that 504 people were employed in the formal wear and costume rental business in Illinois in 2011 good news or bad news? Without some specific knowledge of the industry, the easiest thing to do is look at how much employment figures have changed over time. As it turns out, the formal wear rental business shrunk by 25 percent from 2010 to 2011, according to the Census data.
In the following interactive map, you can compare any two years of data for any industry and see how they measure up. Use the slider at the bottom to change the time frame and use the menu to select an industry. You can type in a few letters of the word you're looking for to narrow down this long list.