That seems like a pretty big difference to gloss over. Why are they publishing probabilities for if the event were to happen today? The event isn't happening today!
There are two types of people consuming these projections. I'll call them the sportsbook type and the newspaper reader. The sportsbook consumers want to know what the probabilities are for the actual event, when it occurs (election day). The newspaper consumers want to know what is going on currently and the country's political temperature.
538's forecasts, especially far from election day, are for the newspaper consumer. They provide insight into current political dynamics, and a quantitative look at how people view policy, the economy, where current fundraising is at, etc. in a single concise number that can serve as the basis for further discussion and analysis. They however aren't useful for the sportsbook consumer, because they don't account for the practically innumerable "unknown unknowns" that will occur between now and election day (scandals, terrorist attacks, fluctuations in the economy, flubs on the campaign trail, external activist efforts gaining traction). If they did account for all that uncertainty, then the predictions consistently be near 50-50 for the majority of the race, which not only is still uninteresting for the sportsbook types, but also means you no longer are providing value to the newspaper types.
Its important to point out that, over time, the predictions become applicable to both readers. As election day nears, the number of "unknown unknowns" decreases, and a prediction for "what would happen if an election were held today" and "what will happen on election day" converges. So up until the few months and weeks leading up to election day, the predictions should be taken more as commentary, and then perceived as serious indications of what will occur closer to election day.
They don't exactly gloss over it. They have tons of articles explaining it, but of course the average reader is just going to see the probabilities and run with that, and 538 does have some responsibility to actively explain things upfront in their UI, which I don't think they do a good job at.
> Why are they publishing probabilities for if the event were to happen today? The event isn't happening today!
My guess is that it's extremely out of scope (and probably ultimately infeasible) to try to incorporate these things into their models. Sure, there's a non-zero chance of a candidate being killed by a meteorite, but I think it's fair to ignore that and, if it happens, admit that you didn't even attempt to include the probability of that into your model.
> the average reader is just going to see the probabilities and run with that
The putative “average reader” who does so will see the default view, which is a forecast, not the nowcast, which you must actively shift to in order to see.
> and 538 does have some responsibility to actively explain things upfront in their UI,
Like, on the view selector that you have to use to choose the nowcast instead of the default forecast, where the nowcast is described as “Now-cast / Who would win the election if it were held today”.
Your personal meteorologist presumably predicts rain on days in the future, when it could happen, not days in the past.
Nate publishes predictions for events that will never occur pr(x wins | election today) when there is no election. It would be like me placing bets on a sports game that is not scheduled to be played.
Nate hasn't been trying to predict elections that far out, either, to be fair. He has always said some variant of "if the election were held today" when discussing the model.
Because this is what every election poll does. Nobody asks people if they would vote in such person a year from now. They always ask what is your voting preference today. If Nate Silver did something different, then he would be completely wrong.
If Nate Silver took the predictions for "if the event were to happen today" and pretended it was a prediction for the future event, he'd be wrong, but that's how most people interpret his predictions anyway so that makes him effectively wrong anyway.
Exit polls are of course asking for voting preference today, because no person in their right mind would ever answer differently for "who would you vote for today?" versus "who will you vote for on November 4?" so it doesn't matter.
The problem is, we don't care about what would happen if the election were to be run today. We care about what will happen when the election actually occurs. What we want is a prediction that takes the polls into account but also factors in all the other information we have that could be used to try and predict the future election (e.g. trying to identify whether changes in a candidates polling numbers are likely to be temporary or reflect a permanent shift, identifying historical trends that can be used to predict future behavior, etc). I realize that predicting the future is much harder than predicting the hypothetical of what would happen today, but predicting the future is the whole point of forecasting.
There is value in being able to tease out the "accurate" voter sentiments today from the various polls and accounting for uncertainty and error, but that value is primarily in how we can then turn around and use that information to aid in future forecasting, and how candidates can use that data to gauge the effects of what they're doing. But without an attempt at forecasting the future, this is largely useless to the general population.
> that's how most people interpret his predictions anyway so that makes him effectively wrong anyway.
The only thing these people need is to learn what he's really doing, and then he will be immediately correct again! To me this seems like the simple and obvious solution to this debate.
