Here are two more takes at it. First, courtesy of UNC Ph.D. student Brice Acree, takes my original plot and then adds an underlying measure of uncertainty—essentially, the margin of error for the estimated margin of victory.
Second, spurred on by a friend who is also a pollster, I calculated a different quantity—called “A” in the piece by Martin, Traugott, and Kennedy—that also captures predictive accuracy, is more robust to how polls treat undecided voters, and allows me to calculate a confidence interval. [cont.]
John Sides, George Washington U. (The Monkey Cage)