Forecasting or Predicting is the act of making statements about what will happen in the future (and in some cases, the past) and then scoring the predictions. Posts marked with this tag are for discussion of the practice, skill, and methodology of forecasting. Posts exclusively containing object-level lists of forecasts and predictions are in Forecasts.

Above all, don’t ask what to believe—ask what to anticipate. Every question of belief should flow from a question of anticipation, and that question of anticipation should be the center of the inquiry.
—Making Beliefs Pay Rent

Forecasting allows individuals and institutions to test their internal models of reality. A forecaster with a good track record can have more confidence in future predictions and hence actions in the same area as they have a good track record in. Organisations with decision-makers with good track records can likewise be more confident in their choices.

Crucially, forecasting is a tool to test decision making, rather than a tool for good decision making. If your decision makers are found to be poor forecasters, that is a bad sign, but if your decision making process doesn't involve forecasting, it's not a bad sign. It's not clear that it should.

Where to start

Some common recommendations for getting into forecasting are as follows:

Track your personal forecasts. Get a notebook, spreadsheet or fatebook.io and write what you think will happen and a % or odds chance. Follow up on it later.
Bet fake money on manifold.markets. It's still pretty addictive, so if you have a gambling problem, please avoid.
Take part in the monthly estimation game. Test your ability to estimate quantities. This is correlated with your ability to navigate the world well
Forecast on metaculus.com. Questions are often pretty focused on geopolitics
Read Superforecasting by Philip Tetlock. This is if books are a way you learn well.

Forecasting Techniques

Forecasting is hard but many top forecasters use common techniques. This suggests that forecasting is a skill that can be learnt and practised.

Base rates

Reference Class Forecasting on Wikipedia

Suppose we are trying to find the probability that an event will occur within the next 5 years. One good place to start is by asking "of all similar time periods, what fraction of the time does this event occur?". This is the base rate.

If we want to know the probab...