7 docs tagged with "probability"

Availability Heuristic — one of the most studied cognitive biases in psychology and behavioural economics, with documented effects across professional, financial, and personal decision-making domains.

Bayesian Thinking is a framework for updating beliefs in proportion to evidence. Named for the Reverend Thomas Bayes, whose theorem formalizes the mathematics of belief revision, it provides a principled method for incorporating new information into prior beliefs — neither overreacting to single data points nor clinging to existing views against contradicting evidence. It is the foundation of modern statistics, machine learning, and rational decision-making under uncertainty.

Expected Value (EV) is a mathematical framework for decision-making under uncertainty that calculates the probability-weighted average of all possible outcomes. By making the implicit trade-offs in any risky decision explicit and quantitative, EV provides a principled basis for comparing investments, bets, and choices across different probability and payoff profiles — even when no single outcome is guaranteed. It is the foundation of rational decision-making in investing, game theory, and any domain where outcomes are uncertain.

The Gambler's Fallacy is the mistaken belief that independent random events are influenced by previous outcomes — specifically, that a sequence of outcomes in one direction makes the opposite outcome more likely. It arises from a misunderstanding of randomness and the representativeness heuristic, and leads to systematically flawed predictions in gambling, investing, sports, and any domain involving independent probabilistic events.

The Hot Hand Fallacy is the belief that a person who has experienced recent successes in a random or semi-random process has a higher probability of continued success — that they are "on a hot streak" and will continue to perform well. First studied by Gilovich, Vallone, and Tversky (1985) in basketball, it is the mirror image of the Gambler's Fallacy, and its relationship with genuine skill-based streaks is more nuanced than originally thought.

The Kelly Criterion is a mathematical formula developed by Bell Labs scientist John L. Kelly Jr. in 1956 that calculates the optimal fraction of a bankroll to bet on a favorable wager in order to maximize the long-run growth rate of wealth. It is widely used by professional gamblers and quantitative investors as a position-sizing rule. The full Kelly allocation maximizes expected logarithmic utility; fractional Kelly (typically 25–50% of full Kelly) is preferred in practice to reduce volatility while preserving most of the growth advantage.

The Representativeness Heuristic is a cognitive shortcut used to estimate the probability of an event by comparing it to an existing mental prototype or stereotype. Identified by Tversky and Kahneman in 1972, this mental model explains why we commit the "Conjunction Fallacy," ignore statistical base rates, and fall for the Gambler's Fallacy. By understanding how the brain prioritizes "story fit" over "statistical reality," decision-makers can avoid expensive hiring errors, improve investment accuracy, and neutralize systemic prejudice in organizational systems.