Dylan Matthews sprinkles grains of salt on Sam Wang’s analysis:
It’s worth noting … that other models give different results. John Sides and the team at the Monkey Cage have a model that uses GDP, the president’s party and approval rating, incumbency, and district-level presidential vote, rather than House polling. Their model gets the seat margin wrong by 2.61 seats, on average, much lower than Wang’s error. It gives Republicans a three out of four chance of keeping the House.
So Wang’s model isn’t definitive. But it does mean one should keep an eye on Congressional ballot polls going forward.
The Dish 