Article
Outcome Bias and Data-Driven Decision-Making Under Uncertainty
In the past, I judged my decisions by outcomes. Over time, I recognised that many choices I once deemed "bad" only had an unfavourable impact. Today, I realise that what truly matters in a decision is not the outcome but its optimality given the circumstances and available information, or, more accurately, how closely the decision approximates the optimal one.
Risk Tolerance: Why a Losing Decision Can Be Optimal
How should we approach decision-making in marketing and advertising, especially under uncertainty? Can a decision with a negative outcome be more optimal than one with a positive outcome? Yes. Judging a decision by its result rather than its reasoning is called outcome bias.
During my experience in decision-making in marketing and optimising budgets for online advertising, I have discovered that specific days within seasonal campaigns present exceptional opportunities. However, capitalising on these opportunities requires embracing a higher level of risk than on ordinary days. It is impossible to rely on data from the previous day with certainty, and waiting a few hours for data on a given day means the irreversible loss of many opportunities.
Without divulging sensitive details, the essential lesson I have gathered is that accepting a higher level of risk in these cases is advisable. Rather than fixating on individual situations, I focus on a 70% probability of a positive outcome in these cases. With this probability in mind, each decision of this type can be considered suitable, regardless of the impact of a single decision. What is important here is the high probability that the profit of decisions with a positive effect will cover the losses. In other words, I am acting on expected value: across many such decisions, the average result is positive even when a single one fails.
The Law of Large Numbers and Expected Value
I strive to implement this mindset when making all managerial or investment decisions. My anchor in these uncertain waters is the weak law of large numbers. It states that as the number of trials increases, the average of the outcomes will likely converge to the expected value. Through the lens of probability, I can maintain a strategic perspective, ensuring that, for example, my approach to online advertising optimisation remains resilient in the face of uncertainty.
The Gambler's Fallacy
The law of large numbers is easy to misread. It does not promise that a bad run will soon be balanced by a good one. Believing that a losing streak makes a win overdue is the gambler's fallacy, and it is exactly the wrong lesson. The law says nothing about the next trial; it speaks only about the average across many. Each decision stands on its own probability, not on what came before it.
Regression to the Mean
A related but distinct pattern is regression to the mean. An exceptional result rarely repeats. A campaign day that vastly outperforms, or one that collapses, is usually part luck, and the next result tends to drift back toward the average. It is why I try not to over-react to a single outcome, good or bad, and instead ask whether the process behind it was sound.
After reading this, it may seem like a simple thing. But answer this: how many people around you judge their steps by results alone?
Continue reading at: I make mistake after mistake
Summary
Common questions on this article's topic
Should a decision be judged by its outcome or by its quality?
What is the Weak Law of Large Numbers and how does it apply to business decisions?
How should you make decisions in marketing when data is incomplete?
What does it mean to be process-oriented rather than result-oriented?
Can a decision with a negative outcome still be the right decision?
Why do most people struggle with decision-making under uncertainty?
What is outcome bias?
What is expected value?
What is the gambler's fallacy?
What is regression to the mean?
What is thinking in bets?
What is decision theory?
How can you make better decisions under uncertainty?
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