It’s possible that the AP’s explanation will ultimately make sense, but the fact that it took multiple inquiries to get to this point is not a good thing. Media outlets in general should be more comprehensive in their reporting of the fiscal impact of government programs, and more transparent in explaining the choices they make. That means acknowledging that these figures, whatever their provenance, have uncertainty built in. Had the AP done that from the start, it could have saved itself a lot of trouble.

There’s another lesson here, too, which is that the use of decimal notation in all the stories obscures the enormous gap between the different figures. The difference between the AP’s figure and the CBO estimate used by the Times and the Journal might not seem thatbig. But it amounts to nearly 59 percent of the entire federal economic stimulus package (though, admittedly, over a longer time horizon). That’s a staggering sum of money, but one that might be glossed over by many readers because of the way it’s rendered on the page (or the screen).

How to get around this? It’s a challenge, and there’s no simple rule—in this case, a “here’s how much this will cost each taxpayer” box wouldn’t have been very illuminating. But unpacking these numbers, and bringing them down to human scale, is the best way to ensure that they’re understood.

Update 2, 7/22/09: Roll Call has weighed in with its own take on the subject, and pegs the bill’s gross cost at “more than $1.6 trillion.”

Not enough numbers for you? You can read Elmendorf’s blog post on the subject, or the full CBO report, here.

Greg Marx is a CJR staff writer. Follow him on Twitter @gregamarx.