The Iowa caucuses are small, but that doesn’t matter so much if the participants are representative of the political parties they’re meant to speak for. And, in 2008, they were.

-In 2008, Iowa caucusgoers aren’t much more strongly partisan than registered party members generally. In an October 2007 poll, 50% of Republicans were “strong” Republicans. In a January 2008 post-caucus poll, 56% of Republican caucus-goers were “strong” Republicans. The comparable fractions among Democrats were 45% and 49%. These are pretty small differences.

-On the GOP side, you might think that caucusgoers were more religious or evangelical or concerned about social issues. Not really. In the October 2007 poll, 37% of registered Republicans called themselves “born again.” In the January 2008 poll, 41% did. Consider also the percentage who said that abortion was “very important” for their presidential vote: 41% of registered Republicans vs. 47% of Republican caucusgoers. The same small difference emerges among those who prioritized gay marriage: 36% of registered Republicans vs. 33% of Republican caucusgoers.

That comes from John Sides’ summary of the pro-caucuses book, ‘Why Iowa?’. But there is, Sides notes, a caveat to these numbers: “High caucus turnout in 2008 may have rendered caucusgoers more representative of party members generally. If 2012 sees substantially lower turnout, caucusgoers could be less representative.” So keep that in mind. “Nevertheless,” he concludes, “claims about unrepresentativeness Iowa caucusgoers tend to run well ahead of the data.”