Comment by maxbond
3 years ago
> I don't even know what that means.
If you have a question I'm happy to clarify. If a restatement is helpful, the problem is that this definition of probability is limited and fails to capture the complexity of the problem domain, not that the problem domain is meaningless.
You're misunderstanding the terminology, "events" refers to sets of potential outcomes (eg, when rolling a die, the outcomes are 1-6 and the event "even" is the set of 2,4, and 6).
(I don't know 538's actual methodology, consider the below an illustration rather than a literal description of 538's model.)
The outcomes here would be each way the electoral vote could possibly be allocated, based on the number of states and the idiosyncracies of each state constitution. The events would be the division of these outcomes by who wins the election in that instance. The model then seeks to attach a weight to each outcome based on how likely it is.
You can think of these weights as the volume of each outcome. We use some kind of model to assign them. The most straightforward model would be to repeat an experiment many times and then assume the rate at which the outcome appears in your sample is approximately the same as it is globally. Other times that isn't possible and you need to use more sophisticated modeling techniques. I'm not going to offer a defense of statistics and machine learning writ large, but I think looking around it should be pretty clear these things can work well even if there's a lot of art to getting it right.
You can imagine comparing the probabilities of each event by pouring their constituent outcomes into separate graduated cylinders so that you can compare their cumulative volume. If you divide their volume by the total volume of all outcomes, that's the probability of that event. Or rather, that's the estimate of the probability, given our model and the data we have.
This is more or less my drunk history version of measure theory and probability theory. I imagine I've gotten some details wrong, so I'd encourage anyone interested to check the subjects out for themselves. Here's some YouTube videos:
https://youtube.com/playlist?list=PLBh2i93oe2qvMVqAzsX1Kuv6-...
https://youtube.com/playlist?list=PLUl4u3cNGP60hI9ATjSFgLZpb...
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