I’ve said this before, but seeing various speculation on the web about how people will view Obama’s and McCain’s VP choices reminds me that, as far as the empirical findings go, the Vice Presidential nominees appear to have almost no effect on the vote. It’s about +3 percentage points in the VP’s home state, and that’s about it.

Actually, there’s not much evidence that even the Presidential nominees have much effect. (See Steven Rosenstone’s 1984 book, Forecasting Presidential Elections, for more on this.) Candidates do benefit slightly by being political moderates–but it’s only a couple of percentage points, so not a huge effect.

About 1/3 of VP’s have become President, and so arguably the VP choice should make a difference in how people vote–but, then again, given that even the presidential nominee isn’t crucial (as we say, people tend to vote the party, not the candidate), it all makes some sense.

With all that in mind, feel free to opine about Biden’s and Palin’s suitability to govern, but I suggest you think twice before opining on how “the voters” will react to this or that.