中级微观经济学范里安课件ch6.ppt

中级微观经济学6 Chapter Six Demand 需求 Properties of Demand Functions Comparative statics analysis （比较静态分析）of ordinary demand functions -- the study of how ordinary demands x1*(p1,p2,y) and x2*(p1,p2,y) change as prices p1, p2 and income y change. Structure Own-price changes Price offer curve （价格提供曲线） Ordinary demand curve Inverse demand curve （反需求函数） Income changes Income offer curve （收入提供曲线） Engel curve （恩格尔曲线） Cross-price effects Own-Price Changes How does x1*(p1,p2,y) change as p1 changes, holding p2 and y constant? Suppose only p1 increases, from p1’ to p1’’ and then to p1’’’. Own-Price Changes Own-Price Changes Own-Price Changes The curve containing all the utility-maximizing bundles traced out as p1 changes, with p2 and y constant, is the p1- price offer curve. The plot of the x1-coordinate of the p1- price offer curve against p1 is the ordinary demand curve for commodity 1. Own-Price Changes What does a p1 price-offer curve look like for Cobb-Douglas preferences? Own-Price Changes Own-Price Changes What does a p1 price-offer curve look like for a perfect-complements utility function? Own-Price Changes Own-Price Changes What does a p1 price-offer curve look like for a perfect-substitutes utility function? Own-Price Changes Own-Price Changes Usually we ask “Given the price for commodity 1 what is the quantity demanded of commodity 1?” But we could also ask the inverse question “At what price for commodity 1 would a given quantity of commodity 1 be demanded?” Own-Price Changes Own-Price Changes Own-Price Changes Own-Price Changes Own-Price Changes Taking quantity demanded as given and then asking what must be price describes the inverse demand function of a commodity. Own-Price Changes Own-Price Changes Meaning of the Inverse Demand Function At optimal choice Or If taking good 2 as money on other goods, then p2=1 and p1=MRS. This is the marginal willingness to pay. Income Changes How does the value of x1*(p1,p2,y) change as y changes, holding both p1 and p2 cons