They do not only predict top-line presidential results, but every race, in every state, for president, House, and Senate. Non-independence is accounted for in the model, so they have no qualms about you judging them by the calibration of their predictions, I. e. You want roughly 60% of their “60%” forecasts to be right, and 40% to be wrong. If all of the races they predict 60/40 go to the more likely candidate, they themselves consider this a failure: https://fivethirtyeight.com/features/how-fivethirtyeights-20...

> I can't think of a similar way to evaluate Silver's election forecasting mode

You bucket every prediction, look at the outcome, and then confirm whether the favoured outcomes in the 8th decile actually occurred 70% to 80% of the time.

You can’t come up with a way to compare his predictions with how the elections end up turning out? Can’t you look up the results of each election?