We haven’t had that much to say about Mitt Romney’s choice of a vice-presidential nominee — mostly because it just isn’t something that lends itself to rigorous analysis.
But let’s focus on the part of the problem where our tools — particularly, the simulation program that runs the FiveThirtyEight presidential forecast — come in handy. Whatever else they do or do not accomplish for Mr. Romney, his potential running mates could improve his standing in their home states, potentially changing the outcome there.
Mr. Romney should not expect any miracles from his choice of a running mate. Historically, they have gained their ticket a net of two percentage points, give or take, in their home states.
How much of a difference could two points make in a state like Florida? And how much would this affect the overall electoral calculus? The simulation program can measure these effects.
Perhaps, however, we have gotten ahead of ourselves. The effect of the vice-presidential nominee varies a bit from election to election and from candidate to candidate. So as a prerequisite, we should ask: which of Mr. Romney’s potential running mates are actually popular back at home?