北京大学：《微观经济学》Chapter Sixⅸ Demand 需求

Chapter six Demand 需求

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 x,*(p1,p2,y)and X2 (p1,P2,y)change as prices p1, p2 and income y change

Properties of Demand Functions uComparative 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 nverse 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

Structure u Own-price changes – Price offer curve （价格提供曲线） – Ordinary demand curve – Inverse demand curve （反需求函数） u Income changes – Income offer curve （收入提供曲线） – Engel curve （恩格尔曲线） u Cross-price effects

Own-Price Changes 4 How does x, (p1, p2,y) change as p, changes, holding p2 and y constant? Suppose only p, increases, from p1 to p, and then to p1

Own-Price Changes uHow does x1 *(p1 ,p2 ,y) change as p1 changes, holding p2 and y constant? uSuppose only p1 increases, from p1 ’ to p1 ’’ and then to p1 ’’’

Own-Price Changes Fixed p2 and y P1X1 p2x2 =y P1=p X1

x1 x2 p1 = p1 ’ Fixed p2 and y. p1x1 + p2x2 = y Own-Price Changes

Own-Price Changes Fixed p2 and y P1X1 p2x2 =y P1=p p1=p X1

Own-Price Changes x1 x2 p1= p1 ’’ p1 = p1 ’ Fixed p2 and y. p1x1 + p2x2 = y

Own-Price Changes Fixed p2 and y P1X1 p2x2 =y Pup p p1=p1 X1

Own-Price Changes x1 x2 p1= p1 ’’ p1= p1 ’’’ Fixed p2 and y. p1 = p1 ’ p1x1 + p2x2 = y

Own-Price Changes Fixed p2 and y X2 pup x1*(p1)

x2 x x1 1 *(p1 ’) Own-Price Changes p1 = p1 ’ Fixed p2 and y

p1 Own-Price Changes Fixed p2 and y X2 pup p x1(P1)x1 x1*(p1)

x2 x x1 1 *(p1 ’) p1 x1 *(p1 ’) p1 ’ x1 * Own-Price Changes Fixed p2 and y. p1 = p1 ’

p1 Own-Price Changes Fixed p2 and y X2 p1=p1” p x1(P1)x1 1(p1)

x2 x x1 1 *(p1 ’) x1 *(p1 ’’) p1 x1 *(p1 ’) p1 ’ p1 = p1 ’’ x1 * Own-Price Changes Fixed p2 and y