A regular, honest review of why you acted — separating skill from luck so you improve the right things.
This capstone of discipline ties the module together: the habit of regularly and honestly reviewing your decisions — not just your profit and lossA record of revenue, costs and profit over a period.. Because markets are probabilistic, judging yourself by results alone teaches the wrong lessons; you must review the quality of your decisions.
The decisive principle (echoing detachment from outcome):
review your decisions and process, not just your results — because in a probabilistic game, a good decision can lose and a bad one can win, so results alone mislead about what to improve. If you only look at
P&LA record of revenue, costs and profit over a period., you’ll “learn” to repeat lucky-but-bad decisions (they made money) and abandon sound-but-unlucky ones (they lost) —
outcome bias corrupting your education. A proper review asks of each decision:
“given what I knew at the time, was this a sound, well-reasoned choice following my process and risk rules — regardless of how it turned out?” This sorts every outcome into four boxes: good decision + win (repeat), good decision + loss (repeat — it was right, just unlucky), bad decision + loss (fix), and crucially
bad decision + win (fix anyway — you got lucky and must not repeat it). Reviewing this way — ideally using your
journal (which recorded reasoning and emotion) on a
regular schedule — lets you
separate skill from luck and improve the
right things: reinforcing good process, eliminating recurring errors, and refusing to let lucky wins validate bad habits. It’s how raw experience becomes genuine
improvement rather than just accumulated outcomes. The disciplined investor’s scorecard isn’t “did I make money?” but “did I make good decisions?” — because over time, consistently good decisions are what
produce the money.
- The principle — review decision quality/process, not just results; good decisions can lose and bad ones win (probabilistic game).
- The danger of results-only — outcome bias: you repeat lucky-bad decisions and abandon sound-unlucky ones.
- The four boxes — judge each decision good/bad independently of win/loss; fix bad decisions even when they won.
- How — use your journal, review on a schedule, separate skill from luck, and improve the right things (process).
ExampleIn her monthly review, Sara finds a trade that won — but only because a reckless oversized gamble happened to pay off (a bad decision, lucky outcome). Results-only thinking would praise it; decision-review flags it as a mistake to fix before the luck runs out. She also finds a losing trade that perfectly followed her process — decision-review keeps it (good decision, unlucky). She’s improving the right things — process — not chasing outcomes.
Key takeawayReview your decisions and process, not just results — in a probabilistic game, good decisions lose and bad ones win, so results-only review breeds outcome bias (repeating lucky-bad choices, dropping sound-unlucky ones). Judge each decision’s quality independently of its outcome (fix bad decisions even when they won), using your journal on a schedule. The scorecard is “did I decide well?” — good decisions produce the money over time.