Does it matter who won in Iowa?

Here’s the form book for the Iowa Presidential caucuses:

• On the Democrat side, the previous three winners all went on to be their party’s nominee. It’s five out of seven overall since 1980.
• On the Republican side, the previous four winners all went on to be their party’s nominee, and again it’s five out of seven since 1980.

If you look at only those contests where there was no incumbent President or Vice-President standing (as was the case yesterday for both sides), then the Iowa winner went on to be their party’s nominee four out of seven times overall: Reagan lost in 1980 to HW Bush, Dole won in 1996, GW Bush won in 2000; Mondale won in 1984, Dukakis lost to Gephardt in 1988, Clinton lost to Harkin in 1992, Kerry won in 2004.