《微观经济学》清华大学课件 Ch3 Preferences消费者偏好[精选].ppt

Chapter Three Preferences 消费者偏好 Where Are We in the Course? We are studying the 1st of the three blocks of microeconomics: Consumer behavior, production theory, and market equilibrium Within the 1st block, we are working on the 2nd of the three components: choice set, preference, and consumer demand What Do We Mean by Preference? (偏好) It refers to the ordered relationship among alternative choices given by an economic agent. In most economic literature, consumer preference is treated as the ultimate exogenous element. Preference Relations Comparing two different consumption bundles, x and y: strict preference: x is more preferred than is y. weak preference: x is as at least as preferred as is y. Indifference: x is exactly as preferred as is y. Notations denotes strict preference;  ~ denotes indifference; denotes weak preference; Preference Relations x y and y x imply x ~ y. x y and (not y x) imply x y. Assumptions about Preference Relations Completeness: For any two bundles x and y it is always possible to make the statement that either  x y or y x. Assumptions about Preference Relations Reflexivity: Any bundle x is always at least as preferred as itself; i.e. x x. Assumptions about Preference Relations Transitivity: Ifx is at least as preferred as y, andy is at least as preferred as z, thenx is at least as preferred as z; i.e. x y and y z x z. Indifference Curves无差异曲线 (或,无差异集) Take a reference bundle x’. The set of all bundles equally preferred to x’ is the indifference curve containing x’; the set of all bundles y ~ x’. Since an indifference “curve” is not always a curve a better name might be an indifference “set”. Indifference Curves Indifference Curves Indifference Curves Indifference Curves Indifference Curves Indifference Curves Cannot Intersect ! (不相交!) Indifference Curves Cannot Intersect Sl