FoMind

Forecasting lessons

From conditional probability and Bayes to cognitive biases, 29 short lessons build your probabilistic thinking. Each takes a few minutes; the FoMind app adds interactive demos, quizzes and practice tasks.

8 modules · 29 lessons · about 225 min

0Forecasting Basics

Learn to ask checkable questions, express confidence as numbers, and read the Brier score and calibration curve that measure how good your forecasts are.

  1. 0.1What Makes a Good Forecasting Question6 min read
  2. 0.2What Does a Probability Actually Mean?7 min read
  3. 0.3Reading Brier Scores and Calibration Curves8 min read

1Conditional Probability

Tell P(A|B) from P(B|A), judge whether events are independent, and see how quickly probabilities shrink when conditions stack up.

  1. 1.1Conditional Probability: P(A|B) ≠ P(B|A)8 min read
  2. 1.2Independence and Correlation7 min read
  3. 1.3The Conjunction Fallacy: More Conditions, Lower Odds8 min read

2Base Rates & the Outside View

Learn to ask “how often does this kind of thing happen?” first, then adjust in proportion to the specific evidence.

  1. 2.1Reference Classes: How Often Does This Kind of Thing Happen?8 min read
  2. 2.2Outside First, Then Inside: Start From the Base Rate and Adjust8 min read

3Bayesian Reasoning

Use the 1,000-person grid and likelihood ratios to combine base rates with the strength of new evidence.

  1. 3.1Bayes With Frequencies: The 1,000-Person Grid9 min read
  2. 3.2Base-Rate Neglect: What a Positive Checkup Really Means8 min read
  3. 3.3Likelihood Ratios: How Strong Is the Evidence?9 min read

4Updating Beliefs and Weighing Evidence

Learn to adjust your probabilities in proportion to the evidence, without being swept away by one headline or ignoring evidence that piles up.

  1. 4.1How Much Should New Evidence Move You?8 min read
  2. 4.2Overreaction and Underreaction7 min read
  3. 4.3Update Often, in Small Steps7 min read

5Cause and Effect

Tell correlation from causation, spot confounders, reverse causation, selection bias, and regression to the mean, and test your reasoning with counterfactuals.

  1. 5.1Correlation Is Not Causation8 min read
  2. 5.2Confounding Variables7 min read
  3. 5.3Reverse Causation and Selection Bias8 min read
  4. 5.4Regression to the Mean8 min read
  5. 5.5Counterfactuals: What If There Were No X?8 min read

6Decomposition and Fermi Estimation

Break hard questions into estimable pieces and use simple multiplication and addition to reach numbers you can defend.

  1. 6.1Break Big Questions into Smaller Ones8 min read
  2. 6.2Fermi Estimation8 min read

7Cognitive Biases

Meet the eight thinking biases that most often distort forecasts, and learn to guard against them when forecasting and spot them when reviewing.

  1. 7.1Overconfidence9 min read
  2. 7.2Anchoring8 min read
  3. 7.3Confirmation Bias8 min read
  4. 7.4The Availability Heuristic7 min read
  5. 7.5Hindsight Bias7 min read
  6. 7.6Outcome Bias7 min read
  7. 7.7The Planning Fallacy8 min read
  8. 7.8The Narrative Fallacy8 min read