Richard Golian

1995-born. Charles University alum. Head of Performance at Mixit. 10+ years in marketing and data.

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Richard Golian

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Outcome Bias and Data-Driven Decision-Making Under Uncertainty

Expected value, decision theory and thinking in bets
Richard Golian
Richard Golian · 5 334 reads
Hi, I am Richard. On this blog, I share thoughts, personal stories, findings and what I am working on. I hope this article brings you some value.

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

I stopped evaluating decisions by outcomes alone. A decision with 70% success probability that fails was still the right call. The Weak Law of Large Numbers: as trials increase, average outcomes converge to expected value. Most people seek certainty. I seek optimality.

Common questions on this article's topic

Should a decision be judged by its outcome or by its quality?
By its quality. A core principle in decision theory holds that a decision should be evaluated based on its optimality given the circumstances and available information, not by the outcome it happens to produce. A well-reasoned decision with a 70% probability of success that fails was still the right call. Annie Duke calls the tendency to judge decisions by outcomes rather than process resulting, and argues it is one of the most common thinking errors.
What is the Weak Law of Large Numbers and how does it apply to business decisions?
The Weak Law of Large Numbers states that as the number of trials increases, the average of the outcomes will converge to the expected value. In practice, this means that a strategy with a positive expected value will produce good results over many repetitions, even if individual outcomes vary. In the article, this principle is used as an anchor for making marketing and investment decisions under uncertainty.
How should you make decisions in marketing when data is incomplete?
In the article, the approach is to accept higher risk during peak opportunities, such as key days in seasonal campaigns, when waiting for complete data means losing the moment. Rather than seeking certainty, the focus is on whether the probability of a positive outcome is high enough to justify the decision across many repetitions. The insight is that irreversible loss of opportunity can be worse than the risk of an individual negative outcome.
What does it mean to be process-oriented rather than result-oriented?
Being process-oriented means evaluating the quality of your decision-making method rather than fixating on individual results. A good process consistently applied will produce good outcomes over time, even if any single decision may fail. This framework, advocated by Annie Duke and grounded in expected utility theory from von Neumann and Morgenstern, separates the skill of decision-making from the randomness of outcomes.
Can a decision with a negative outcome still be the right decision?
Yes. If a decision was optimal given the available information and the probability of success was sufficiently high, a negative outcome does not retroactively make it a bad decision. In the article, this is illustrated through marketing budget allocation during seasonal peaks: a decision with a 70% probability of positive return that happens to fail once is still correct, because over many such decisions, the gains will outweigh the losses.
Why do most people struggle with decision-making under uncertainty?
Because most people are result-oriented and seek certainty. They judge past decisions by what happened rather than by what was knowable at the time. This leads to risk aversion in situations where accepting risk would be optimal, and to overconfidence in situations where outcomes happened to be favourable. Recognising that uncertainty is inherent, and that good decisions can still produce bad outcomes, is the first step toward better judgement.
What is outcome bias?
Outcome bias is the tendency to judge the quality of a decision by how it turned out rather than by how it was made. A sound decision that fails is treated as a mistake, and a reckless one that happens to work is praised. It leads people to learn the wrong lessons from both success and failure.
What is expected value?
Expected value is the average result you would get if you repeated a decision many times, weighting each possible outcome by its probability. A choice with a positive expected value is worth making across many repetitions, even if any single instance can lose. It is the anchor for deciding under uncertainty.
What is the gambler's fallacy?
The gambler's fallacy is the mistaken belief that a run of one outcome makes the opposite outcome more likely next time, as if a losing streak means a win is overdue. In truly random and independent events, the past does not change the odds of the next trial. The law of large numbers describes long-run averages, not short-run corrections.
What is regression to the mean?
Regression to the mean is the tendency for an extreme result to be followed by one closer to the average. An exceptionally good or bad outcome is usually part luck, so the next result drifts back toward the norm. Mistaking this natural drift for the effect of an action is a common error in judging performance.
What is thinking in bets?
Thinking in bets is an approach popularised by Annie Duke that treats every decision as a bet on an uncertain outcome. Instead of asking whether a choice was right because of how it turned out, you ask whether the odds justified it at the time. It separates the quality of a decision from the luck in its result.
What is decision theory?
Decision theory is the study of how to make rational choices under uncertainty. Rooted in the expected utility framework of von Neumann and Morgenstern, it holds that a good decision maximises expected value given the information available, regardless of the single outcome it happens to produce.
How can you make better decisions under uncertainty?
Focus on the process rather than the result. Estimate the probability of success, act when the expected value is positive, and repeat the approach across many decisions so the averages work in your favour. Avoid judging past choices only by their outcomes, and accept that a good decision can still fail.
Richard Golian

If you have any thoughts, questions, or feedback, feel free to drop me a message at mail@richardgolian.com.

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