Chance of Democrats or Republicans winning a House majority over time
Projected House Partisan Control
Distribution of House race control are generated based on 20k simulations.
Chances of a Republican win in the closest House races
Below is the probability of a Republican victory in Senate races within 67% probability.
Probabilities in Republican-held districts won by Clinton
These districts were won by Clinton in 2016 but are represented by a Republican.
Probabilities in Democratic-held districts won by Trump
These districts were won by Trump in 2016 but are represented by a Democrat.
How accurate are our predictions?+−
Our model depends primarily on polls to predict vote outcomes. Past polling error informs our modelling of the uncertainty of our predictions. We model the probabilities using the beta, weibull, and logistic distributions. The Senate partisan control vote and probability is estimated using 20,000 Monte Carlo simulations.
In addition to polls, which we weight as 3/5th of our predictions in our House forecast, we incorporate a k-nearest neighbors algorithm to discern what polls tell us about states with little data.
Credit to Daniel Donner of Daily Kos for shapefiles of the population-adjusted map.