If they were independent, then it would be trivial to update on each of them and arrive at a meta-forecast much greater than 80%. But they’re really not. Many of them are based on the same polls, news, and historical behaviors. They may have different models, but they’re very much not independent forecasts.
If they were independent … But they’re really not.
I agree. That’s why calculating the “combined” forecast is hard—you need to estimate the degree of co-dependency. But as long as the forecasts are not exactly the same, each new one gets you a (metaphorical) bit of information and your posterior probability should creep up from 80%.
If they were independent, then it would be trivial to update on each of them and arrive at a meta-forecast much greater than 80%. But they’re really not. Many of them are based on the same polls, news, and historical behaviors. They may have different models, but they’re very much not independent forecasts.
I agree. That’s why calculating the “combined” forecast is hard—you need to estimate the degree of co-dependency. But as long as the forecasts are not exactly the same, each new one gets you a (metaphorical) bit of information and your posterior probability should creep up from 80%.