More from Why Iowa? by David Redlawsk, Caroline Tolbert, and Todd Donovan:
Even though Iowa contributes only a small number of delegates to the national convention, the Iowa caucuses “matter” a great deal because they affect vote choices through the rest of the nomination process. Two features of the caucus results are especially important: 1) how candidates perform relative to “expectations” going into the caucuses, and 2) how media coverage of the candidates changes immediately following the Iowa caucuses.
Relying on a series of public opinion surveys, the authors demonstrate that in early February 2008, roughly half of the primary voters in the Super Tuesday states were able to correctly identify the winner of the Iowa caucuses. Those that knew this information were more likely to vote for the Iowa caucus winners than those who did not. The authors theorize that this is because performance in the Iowa caucuses helps candidates demonstrate viability (likelihood of winning the nomination) and electability (likelihood of winning the general election).
Thus, the authors argue, it is not necessary for a candidate to win the Iowa caucuses, but it is extremely helpful for their campaign if they 1) do better than expected, and 2) the media increases its coverage of the candidate as a result. If these two conditions are met, the candidate is much more likely to win the New Hampshire primaries and then the rest of the nomination battle.