In other words, a bad recession occurring close to a midterm election isn’t a necessary condition for a disastrous midterm election, but it seems to be sufficient. Because of the problems described above, regression analysis is going to have a hard time picking up on this, especially since we don’t have a good, all-encompassing variable for “the public perceives a bad economy.” But the relationship is pretty obvious nevertheless.

To be fair, there are reasons why this year’s Democrats might avoid blame for unemployment this time. The most obvious reason is that this recession didn’t begin on Barack Obama’s watch. Even if unemployment still is marching upwards, it started going up on his predecessor’s watch, and his party will probably be given at least some credit for this. Additionally, if unemployment begins to decline precipitously – which is possible – people may perceive that the economy is improving. But the latter appears increasingly unlikely, while the former argument is weakened by polls showing the public increasingly places the blame for the state of the economy on the Democrats.

The bottom line is that I don’t think Democrats can find much solace in the lack of a statistically significant relationship between various measures of the health of the economy and midterm election results. If voters think the economy stinks in 2010, common sense and a review of the historical record point toward substantial seat losses for the Democrats. Combined with a President whose numbers are drifting below 50%, and a Democratic party that is dramatically overextended into red territory, these factors increasingly point toward a Republican wave of some magnitude in 2010.