In Praise of Hunches

I like forecasting. I’m not bad at it, my scores on Good Judgment Open are pretty good. If you’ve read Phil Tetlock’s brilliant book Superforecasting (Scott Alexander review here), or some of the other content put out by good forecasters, you might have an impression of how a forecaster comes up with their view about how likely an outcome is. They start by calculating a base-rate. For example, if you want to know whether the Conservatives are likely to win a by-election in the UK, you might start just by figuring out what percentage of the time the government has won in all by-elections in the past 20 or 30 years, rather than delving into the specifics of whatever by-election you’re forecasting. Then you might update your beliefs on the basis of other information - if you started with a base-rate of 5% (or whatever the real base-rate is for governments winning by-elections), you might update a lot if the Conservatives are polling really well. If you’re really smart, you might do somet…