Most post-mortems do not fail because the team lacks effort. They fail because the last metric on the slide becomes the verdict. A launch spikes, so the decision must have been “right.” A pilot stalls, so the decision must have been “wrong.” That shortcut feels efficient, but it trains the organization to chase outcomes instead of improving decision quality.
A Fast Way to Catch Outcome Bias Before It Rewrites the Story
Outcome bias is the tendency to judge a past decision mainly by its outcome, rather than by the information, constraints, and reasoning available at the time. In post-mortems, it shows up as a common shortcut: a good result gets treated like proof the process was good, and a poor result gets treated like proof the process was bad.
Outcome bias isn’t the only issue that can influence people to make suboptimal decisions, of course. If you want information on another subtle bias that can warp your judgment in repeat situations, see The Consistency Trap: How to Make Better Decisions.
Once you know that a bias might be affecting your choices, you then need to identify places where it could show up and determine how strongly it may be affecting you. The fastest way to spot outcome bias is to watch the choices you make in a setting where outcomes resolve fast and repeatedly.
A short drill in a game environment works well for this exercise as it gives you plenty of chances to test yourself on making choices, and many games return the outcome of your choices very quickly. In blackjack, for example, you make a decision, the hand resolves, and your brain tries to grade the choice you just made by whatever happened next. You can test this by using https://www.luckyrebel.la as a real-world example. Choose one of the blackjack games they offer and run a 10-minute “process over outcome” drill. Other games will also work, but blackjack is effective because it has clear states and its rounds are fast-paced. You could also try baccarat, poker, or something similar – but blackjack is likely to be the best option.
To start testing yourself, open a notes app and make notes on each decision you make. For each decision, record the information you had available to you, the choice you made (such as whether to hit or stand), plus an explanation of why you made that decision. After the game finishes, open a separate file and write down the outcome and whether you felt that the choice you made was the right call at the time. After you’ve done this a few times, leave the notes alone and come back to them some time later, once your memories and emotional responses to the game have faded.
Looking only at the first file, reread your notes and decide for each one whether your choices were correct given the information you had at the time. Then compare those notes with how you felt about your choices immediately after seeing the outcomes of the games and see how they differ. This is one of the clearest ways to identify outcome biases in your own thinking.
A Decision Quality Scorecard You Can Use in 5 Minutes
You can bring lessons learned from the above drill back into your real reviews. Before you focus on the results of a project, get everyone to agree on the quality of the choices made during it. This helps the team avoid letting actual outcomes guide their opinions on the project.
While doing this, focus in particular on the following questions:
- Inputs: what did we know then, and what did we not know?
- Assumptions: which assumptions were explicit, and which were implied?
- Thresholds: what evidence would have changed the decision at the time?
- Process: did we follow the process we said we would follow?
- Next experiment: what is the smallest test that improves the next decision?
This format protects learning in both directions. You can say, “The outcome was disappointing, but the decision was defensible,” without sounding like you are making excuses. You can also say, “The outcome looked fine, but the decision process was sloppy,” without sounding combative.
Keeping Outcome Bias and Hindsight Bias Separate
Outcome bias is sometimes confused with the similarly named hindsight bias, but these two things are actually extremely different concepts. If you want a clear explanation of the differences between outcome bias and hindsight bias, the explainer Hindsight and Outcome Bias keeps the concepts clean and practical.
Outcome bias and hindsight bias often travel together, but they distort different parts of the review. Outcome bias weighs the result too heavily when judging the decision. Hindsight bias rewrites the past, so the result feels predictable, which inflates confidence and simplifies cause and effect.
In practice, keep the room focused with two sentences.
First: “Judge the decision using only what we knew at the time.”
Second: “Now that we know the outcome, what new information should update our assumptions?”
When your post-mortems make that separation explicit, they stop rewarding luck and start rewarding good judgment. Over time, people document reasoning, share uncertainty earlier, and improve the process that produces strong decisions, regardless of how any single outcome lands.
