US Election Nowcast – 30th October 2020 2

Current Nowcast

This is our final Nowcast. From tomorrow we will provide a Forecast for what we expect the result to be on Polling Day.

If Trump was hoping for momentum into Polling Day then he has run out of fuel for it.

Although firming up in Texas, elsewhere Trump is falling back. Ohio and Georgia are now firm Biden territory. Elsewhere no momentum is in evidence for Trump. Something dramatic needs to happen for Trump to have a fighting chance on Tuesday.

Probability of Biden Winning State

Presidential Election Forecast Philosophy

Our US Presidential Election forecast is based on polling in individual states. We run a monte-carlo simulation across the entire country and then calculate the probability of each candidate winning each state or electoral district (in the case of Maine and Nebraska). From this we allocate Electoral College votes State by State giving a final total for each candidate.

Do you allocate whole States / Districts to Candidates?

As we approach Election Day, our Nowcast now moves to a full Monte Carlo simulation of the whole country. From this Nowcast onwards our seat forecast is based on allocating the total EC votes for each State / District to the candidate who “wins” in the simulation. From this we produce a probability distribution of likely outcomes.

What do you mean by Strong / Safe / Soft?

We allocate a State a grade on the following basis

Safe – 95% or greater chance of winning or all State’s EC votes allocated to one candidate in EC allocation

Strong – 70% to 95% chance of winning

Soft – 55% to 70% chance of winning

Tie – Less that 55% chance of winning for either candidate

Sites like FiveThirtyEight have a higher probability of Trump winning. What are you doing wrong?

Nothing! 538 uses a different methodology than we do and they are also producing a forecast of polling day, whereas we issue NowCasts (what the result would be today).

Can you tell me what the probability of a certain event happening is?

Sure. We provide the most interesting probabilites above, but it’s easy to calculate things like how likely Biden is to win Texas, Ohio and Florida (1.7% as of this morning). Leave a comment below if there is a particular probability you want us to share with you.