Nate Silver continued the argument about Ames today by presenting data that show the limited effect not of Ames, but of the Iowa Caucuses -- especially on the Republican side. I've got a bit more to say on this, including the importance of the dropout gap between Democrats and Republicans.
To back up a bit...Iowa doesn't have to predict the nominee to be important. As Josh Putnam pointed out in a series of tweets this morning (I'm not going to link to them all; just follow him, and read FHQ), what Iowa does is winnow the field. It matters a lot if you finish 5th or 6th in Iowa, because then your campaign ends and, consequently, you aren't nominated. If Iowa voters have an independent effect that makes the difference between fighting on and being finished, then it certainly does matter!On the other hand, if being an also-ran in Iowa is not an independent effect, but just the consequence of losing the invisible primary, then it's not all that important after all.
I think what the evidence shows is that it's a little of both. Looking at the Democratic side, in 2008 Chris Dodd, Bill Richardson, and Joe Biden were crushed in Iowa (and gone soon thereafter) exactly because they had been trounced in everything else: Iowa registered their failure in 2005-2007, rather than exerting an effect of its own. On the other hand, Iowa probably did have an independent effect on the relative standings of the winners of the invisible primary (Obama and Clinton, and to a lesser degree Edwards). An effect -- but not a decisive one.
Now, the dropout gap. What I suspect that Nate's equation is picking up, at least to some extent, is that Republicans habitually drop out of the race before Iowa, while Democrats don't. Hmmm....I need to be a bit more specific. Some candidates, such as Mitch Daniels and John Thune this cycle or Mark Warner and Evan Bayh last time, drop out before they formally announce their candidacies. In my view, that sort of candidate did in fact run and lost, and they are found on both sides. What Republicans have and Democrats don't are candidates such as Tim Pawlenty this year or Lamar Alexander, Liddy Dole, and Dan Quayle in 2000 -- candidates who ran full-blown campaigns, complete with formal announcement of candidacy, and dropped out before contesting the Iowa caucuses. I don't really know why that's the case. Is it that Republicans are more hierarchical and therefore can winnow more efficiently? Better organized? Is there an Ames factor, in which a highly visible marker during the invisible primary gives candidates a message so obvious that they can't miss it? Or is it learning from party history (correctly or not); Republican longshots don't have the examples of success that Democratic longshots have.
Whatever the reason is, it appears to be quite real. And consequently the line of serious contestants dropping out after Iowa or New Hampshire tends to be longer for the Democrats than for the Republicans.