Firms compare the expected payoffs from alternative actions, such as changing price, output, product design, advertising, or entry, while anticipating how rivals might respond. A best response is the option selected under those expectations. Because the relevant payoff depends partly on competitors’ choices, the preferred action can differ from the one chosen without strategic interaction.
An adjustment can alter the set of choices available to other firms, changing their incentives and expected payoffs. Those firms may then revise their own decisions, creating a chain of responses rather than an isolated change. The resulting interaction can shift the market equilibrium, meaning the market settles at a different pattern of mutually connected decisions.
Consumer responses and changing incentives influence which action appears most profitable to a firm. A demand shock can modify the conditions behind price, output, product-design, advertising, or entry decisions, while the firm still considers competitor reactions. Studying these adjustments shows how external changes redirect strategic choices instead of treating decisions as fixed over time.
An analysis identifies the firms involved, the decisions available to each one, and the expected payoff associated with different combinations of actions. Economists then consider how each firm anticipates rival behavior and determine the relevant best responses. Examining how those responses fit together helps reveal the market equilibrium and the effects of changing conditions.
Game-theoretic analysis is particularly useful for oligopoly situations in which firms may fight over prices, decide capacity, cooperate, or attempt deterrence. These cases require attention to strategic responses because each firm’s outcome depends on how rivals react. Comparing possible decisions and resulting payoffs helps explain why competition can produce different market outcomes.
Researchers can compare firms’ incentives and expected responses before and after regulation, technological change, or a demand shock. The comparison shows whether firms alter prices, output, product design, advertising, or entry decisions and how those changes affect equilibrium. Linking these outcomes to consumer welfare helps evaluate the broader economic consequences of changing market conditions.