National debt clocks are all the rage on Republican lawmakers' websites. Rep. Raul Labrador of Idaho has one. Sen. Tom Coburn of Oklahoma has one, too. At least 54 other lawmakers have them as well. But if you look at the figures on the clocks, you'll notice an obvious discrepancy.
Writing on the blog Smart Politics, University of Minnesota's Eric Ostermeier finds that national debt clocks on congressional websites are far from being in sync. He went through 56 senators' and representatives' websites on Sunday and found 16 different debt values. The discrepancy between the highest and lowest tallies was $758 billion (5 percent of the total debt by Ostermeier's estimate).
The highest estimate comes from Coburn's website, at $17.3 trillion (as of Sunday). The lowest estimate was on fellow Republican Sen. Kelly Ayotte's site at $16.5 trillion (also from Sunday).
According to the Treasury Department, the "total public debt outstanding" is $16.7 trillion (as of March 7). By Ostermeier's calculations, the average of all the clocks was $16.716 trillion, which is basically on point.
In reality, a completely accurate debt clock couldn't be constructed. Or if it could, it wouldn't run smoothly. That's because the rate of cash flowing in and out of the treasury isn't even. Some days it would lurch forward, on others it could even run backward.
The debt is such a slippery number that trying to forecast exactly where it will be is a tall order. That's especially true this year, when Congress may enact differing courses of action on the budget. The Congressional Budget Office outlines the possible scenarios, but it is difficult to pin down an exact projection. This CBO graph from August shows the huge divergence of projections of the debt depending on legislative decisions. There are other aspects that make the debt numbers volatile as well, such as how the stock market performs (that could changes the amount of income taxes paid by investors) and how quickly people file their tax returns.
Of course, displaying the exact debt figure isn't the point of these clocks. Think of them as illustrations. Like the original debt clock in New York City, it's something of a public art installation. The motion and relative size of the numbers are what matters, not the exact numbers themselves.
Your best bet for an accurate reading? The Treasury Department updates its debt figures several times per week. Just not in real time.