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🎲Lecture 3 - Probability and base rates

🚦 Status🟠 Studying

🧠 Mastery🐥 Apprentice

📅 Last Review18 May 2025

Before asking what does this evidence say, ask how often is this true anyway. That is the 🔤 Base rate.
A good test applied to a rare thing produces mostly false alarms. The arithmetic is not optional.
Count in whole packets, not in percentages. The answer becomes obvious.
Vivid detail is not evidence of frequency. It only feels like it.

18:31. the load test failed at a third of volume at 15:10. I am here anyway
probability = long-run share. not a feeling
base rate = how common the thing is before you look at any evidence
people throw the base rate away the moment they get a vivid detail (the 1974 paper, on the reading list)
metal detector example. write it ALL down, do not trust memory tonight
flagged ≠ contaminated. flagged mostly = fine
Rasmus pushed his notes across at 20:40 without saying anything. I had stopped writing

Read 🔬 Judgment under Uncertainty - Heuristics and Biases for the reading response
Do 📌 Statistics I - Problem set 1 - Probability and base rates
Write 🔤 Base rate with one example from work
Redo the metal detector sum on a day when I can think

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