Payoff Matrix
Plain definition
A payoff matrix is a table showing the payoffs each player receives for every combination of strategies in a simultaneous-move game.
In economics
The standard representation of 2-player games in normal form: rows are one player's strategies, columns the other's, and each cell lists (row player's payoff, column player's payoff). It makes dominant strategies and Nash equilibria easy to find by inspection.
Example
A prisoner's dilemma matrix shows payoffs for confess/deny: (-5,-5) if both confess, (0,-10) if one confesses and the other denies, and so on.
Common confusion
Students sometimes read only one player's payoffs from each cell; the matrix lists both players' payoffs, and a cell's numbers are ordered (row player, column player).