How Romney’s Pick of a Running Mate Could Sway the Outcome

… 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? [cont.]

Nate Silver, New York Times