
How to Decide by Annie Duke: Summary & Notes
by Annie Duke
In One Sentence
A practical toolkit for making better decisions under uncertainty — teaching you to separate decision quality from outcome quality, think in probabilities, and overcome the cognitive biases that lead to poor choices.
Key Takeaways
- Resulting is the enemy of learning — a good outcome doesn't mean it was a good decision, and vice versa
- Think in probabilities, not certainties — assign percentage likelihoods to outcomes rather than binary yes/no thinking
- Decisions are bets on the future — you're always working with incomplete information and uncertainty
- The quality of a decision should be judged by the process, not the result
- Hindsight bias makes past events seem more predictable than they were — combat it with pre-mortems
- Identify your preferences before analyzing options to avoid motivated reasoning
- Time travel mentally: imagine yourself in the future to gain perspective on today's decision
- Create a "decision group" of trusted advisors who will challenge your thinking
Summary
A book about how to make decisions. Whether you're after the ability to make better decisions, to make faster decisions, or both, you'll find something of value in here.
May seem a bit basic for those familiar with cognitive biases, but still worth reading. We all make decisions every day, so every improvement we can make will pay dividends.
Who Should Read This Book
- Leaders and managers who make high-stakes decisions regularly
- Anyone who tends to beat themselves up over decisions that didn't work out
- Poker players, investors, or anyone operating under uncertainty
- People who want to reduce anxiety around decision-making
- Fans of behavioral economics who want practical tools, not just theory
Favorite Quotes
- The quality of your life is the sum of the quality of your decisions.
- Hindsight bias is the great enemy of learning from experience.
- Resulting is when we use the quality of an outcome to judge the quality of a decision.
- You can't know if you made a good decision until you know the things you couldn't know at the time you made it.
- Certainty is an illusion. You're always deciding under conditions of uncertainty.
- The way to become a better decision-maker is to focus on the process, not the outcome.
- A pre-mortem is imagining that you've failed and asking why.
- The goal isn't to be right. The goal is to be less wrong over time.
FAQ
What is "resulting" in decision-making?
"Resulting" is Annie Duke's term for judging a decision's quality by its outcome. It's a cognitive error: a decision can be good even if the outcome is bad (and vice versa). A poker player who correctly folds a weak hand isn't wrong if they would have won — they made the right decision with the information available. Resulting prevents us from learning and improving our decision process.
How do you separate decision quality from outcome quality?
Focus on the process, not the result. Ask: Did I consider the right information? Did I think through the probabilities? Did I account for my biases? Duke recommends keeping a decision journal where you record your thinking before outcomes are known. This creates an accurate record of your process, separate from hindsight bias.
What is a pre-mortem and how does it help decisions?
A pre-mortem is a technique where you imagine a decision has failed and then work backward to identify why. Unlike a post-mortem (which analyzes actual failures), a pre-mortem happens before you act. It helps identify risks and blind spots while you can still address them, combating overconfidence and the planning fallacy.
How is How to Decide different from Thinking in Bets?
Thinking in Bets (Duke's first book) introduces the concept of decisions-as-bets and the problems with resulting. How to Decide is the practical follow-up — a workbook with specific tools, exercises, and frameworks for implementing better decision-making. Think of Thinking in Bets as the "why" and How to Decide as the "how."
What is the "happiness test" in decision-making?
Duke's happiness test helps determine how much time a decision deserves. Ask: "How much will this decision affect my happiness in a week? A month? A year?" If the answer is "not much," the decision doesn't warrant extensive analysis. This prevents over-thinking low-stakes choices while reserving cognitive resources for decisions that truly matter.
How do you think in probabilities instead of certainties?
Instead of saying "this will work" or "this won't work," assign percentage likelihoods: "I think there's a 70% chance this succeeds." This forces you to acknowledge uncertainty, consider alternative outcomes, and calibrate your confidence. Duke recommends practicing with low-stakes predictions to improve your calibration over time.
Detailed Notes
Notes
Introduction
- There are only two things that determine your life: luck and the quality of your decisions. And you only have control over your decisions.
- A good tool has a use that can be repeated. Use the tool the same way, get the same results.
1—Resulting
- We tend to look at outcomes of decisions to determine whether a decision was good or bad, rather than looking at the process. This is called "resulting."
- In reality, luck plays a role in every decision.
2—Hindsight
- "Hindsight bias" occurs when we try to remember what we knew and how we felt when we made a decision. It is almost impossible to accurately reconstruct these things after the fact, when we know the outcome.
- Markers of this thinking are things like "I should have known" or "I knew it all along."
- Keeping a decision journal, or writing down what you know when you make the decision, is one way to counter this. You can read it later and remember more accurately.
3—The Decision Multiverse
- We need experience to learn, but individual experiences can interfere with learning.
4—The Three Ps: Preferences, Payoffs and Probabilities
To make better decisions:
- Identify all the possible options for your decision
- Identify the possible outcomes within each option
- Identify your preference for each
- Estimate the likelihood of each option
- Assess the relative likelihood between the outcomes of each option
- Compare the options and decide
Don't forget that the payoffs of each option and outcome can be things other than money: happiness, time, self-esteem, etc.
The downside of pros and cons lists are that they don't take into account the magnitude of the upside or downside, which is critical.
The main tool to improve your decisions: turning stuff you don't know into stuff you do know. In other words, more information.
Another note: the willingness to guess is essential to good decision-making. It forces us to ask how much we really know and why we think we know it.
5—The Power of Precision
- A common problem making decisions with others: you use terms like "probably" but have different ideas what that term means in terms of probability.
- The best way to communicate probability: a specific number, with a range associated with it. For example, "I estimate 60%, with a lower bound of 40% and an upper bound of 80%."
- That range gives other people an idea of how certain that estimate is. Note that this is a "reasonable" range, not a guaranteed range (you'd be shocked if it was outside).
6—Turning Decisions Outside In
- We suffer from all kinds of biases because we view the world from our own perspective, knowledge, and experience.
- One way to counter this is to look at the "base rate," or the overall probability that applies to this situation.
- The other way is to seek a variety of opinions from others with different perspectives.
7—Breaking Free from Analysis Paralysis
- The key to making faster decisions is understanding what the cost is for making a worse decision. If the cost is low, you should go fast. If the cost is high, you should go slow.
- One way to help assess this is to project yourself in the future: will you care about the outcome of this decision tomorrow? In a week? In a year?
- You can also move faster by asking yourself: if this was the only option I had, would I be happy? If yes, make the decision and move on.
- Another good question to ask: "if I pick this option, what's the cost of quitting?"
8—The Power of Negative Thinking
- You can improve your chances of accomplishing a goal by time-traveling to different futures and imagining what got your there.
- First, conduct a "pre-mortem": imagine yourself having failed, and what caused it. This is a good way to encourage others to speak up, and helps identify obstacles.
- Then, do a "backcast": imagine yourself having just succeeded. What got you there?
- Then, commit to doing the things that will increase your chances of success, and prepare you for a better reaction when things go wrong. Planning ahead will help you avoid reacting emotionally.
9—Decision Hygiene
- Don't tell someone your opinion before asking them theirs. It will bias their response.
- If in a group, get opinions from team members individually first. Then you can share those opinions with the group.
- Making individual feedback anonymous can also help elicit better feedback, and prevent groupthink.
- Be careful how you present the background information for the decision too. This can affect the feedback you get.




