Larry Bartels, a political science professor at Princeton, has gotten a lot of play in "the internets" (as a friend of mine calls it) for his argument that Democratic presidents help create more economic growth and more egalitarian distributional effects than their GOP counterparts, at least since WWII. Jim Manzi's dismantling of at least the inequality claims over at NRO almost make me wish I had spent more time doing stats in grad school and less reading Plato or whoever. Well, almost.
What's remarkable about Manzi's analysis - and deadly for Bartels' claims - is that he makes clear that Bartels is playing a shell game with his numbers. When calculating presidential effects, Bartels gives himself a "lag year" and so Jimmy Carter gets credit for whatever happens economically for a year after he stopped being president. (That's 1980 for you young'uns). But as Manzi shows, if you get rid of the lag year or make it two years, all of Bartels' effects disappear. Poof! Now, maybe there's something robust about a year, but my guess is that Bartels fidgeted around a bit with the lag until he got what made sense to him.