How to decide, especially when the information is incomplete.
Judge a decision by what was knowable when it was made, and keep the outcome in a separate column.
Reviewing a trade or a deal that went wrong, answering a question about a failure, and any post-mortem.
From Thinking in Bets · Annie Duke
Evidence about demand comes from what people have already done and paid for, not from what they say they would do.
Customer discovery, commercial due diligence, and any interview that asks how you would validate a product idea.
From The Mom Test · Rob Fitzpatrick
Check whether the metric is still the goal or has become the goal, and reserve the heavy process for decisions that cannot be undone.
Product and leadership questions, assessing a large company's culture, and deciding how much process a decision deserves.
From Amazon's 2016 letter to shareholders (Day 1) · Jeff Bezos
Most offers come from a few deeply prepared applications, so prepare deeply rather than widely.
Deciding where to apply, how many applications to make, and how to allocate the weeks before deadlines.
From The 80/20 Principle · Richard Koch
Tell investors in advance that you will optimise long-term cash flows over reported earnings, then do it, so the market can price the choice rather than be surprised by it.
Any growth company valuation, any founder letter, and the interview question of how to value a company that reports no profit.
From Amazon's 1997 letter to shareholders · Jeff Bezos
Ask what would make this fail and who is paid for what before asking anything else.
Diligence, deal structuring, reading any management proposal, and preparing for any decision you cannot easily reverse.
From Poor Charlie's Almanack · Charles T. Munger
The fair test of a decision is the information available when it was made; hindsight is a different exam.
Discussing the Lehman decision, or any post-mortem where later knowledge is contaminating the judgement.
From Inside the Meltdown · 2009
State the liquidity first, because the argument that prices overshoot value is only available to those who can wait.
Any crisis communication, any question about buying in a crash, and infrastructure or real asset valuation.
From Bruce Flatt's March 2020 update to Brookfield shareholders · Bruce Flatt
A firm that did what the rules allowed and lost has not been excused by the rules; management chose the position.
Banking interviews, risk culture questions, and any post-mortem that reaches for the regulator as the explanation.
From JPMorgan Chase letter to shareholders, 2008 · Jamie Dimon
Ask how many people ran the same method and are not in the sample before treating a record as evidence of skill.
Reading any success memoir, evaluating a manager's record, or presenting your own.
From How I Made $2,000,000 in the Stock Market · Nicolas Darvas
The price of risk tracks the mood, so the useful time to buy is when the mood is worst, and the dangerous time is when it is best.
Any question about market timing, contrarian investing or what to do in a crisis.
From Berkshire Hathaway's 2008 letter to shareholders · Warren Buffett
Decide what a business is worth before looking at the price, then act only when the price is far enough below.
Any stock pitch, any conversation about whether a market move is a reason to act, and any valuation that starts from the price.
From The Intelligent Investor · Benjamin Graham
Write the thesis with its test attached: the variant view, the evidence, and the event that would confirm or refute it.
Writing a stock pitch, reviewing a portfolio, and any investment committee that wants to know what would change your mind.
From Greenhaven Road Capital's Q2 2026 letter, on changing how the portfolio is built · Scott Miller
In a disagreement, weight each view by that person's track record on the question, not by their rank or confidence.
Investment committees, group cases, and any time you are deciding whose forecast to trust.
From Principles · Ray Dalio
Decide which mistake is more expensive before tuning a model; the threshold is a business choice the statistics only express.
Any model used for screening, fraud, credit or hiring, and the interview question of how you would evaluate a classifier.
From Precision vs Recall, With a Clear Example · Kimberly Fessel