Thomas12e-Chapter6托马斯管理经济学章6

1-1©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.第6章弹性和需求©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.6-2©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.学习目标（6.1）定义需求价格弹性，并用其预测商品的需求量和价格变化；（6.2）解释价格弹性在价格变动影响总收益变动时如何起作用；（6.3）列举并解释影响需求价格弹性的几个因素；（6.4）计算需求曲线上价格的弧弹性和点弹性；（6.5）指出边际收益、总收益和需求弹性的关系，写出线性需求函数的边际收益的方程；（6.6）定义并计算需求收入弹性和需求交叉价格弹性。6-3©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.需求价格弹性(E)根据需求定理P和Q是负相关的，所以E总是为负~E的绝对值越大,买者对价格变化越敏感•度量消费者对价格变化的反应和敏感程度QEP6-4©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.弹性反应程度E富有弹性单位弹性缺乏弹性表6.1需求价格弹性(E)%∆Q%∆P%∆Q=%∆P%∆Q%∆PE1E=1E16-5©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.给定价格的变化百分比，可以预测需求量的变化百分比~%Qd=%PxE给定需求量的变化百分比，可以预测需要的价格变化百分比:~%P=%Qd÷E需求的价格弹性(E)6-6©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.价格弹性和总收益富有弹性产量效应占优单位弹性没有占优效应缺乏弹性价格效应占优价格升高价格降低TR减少TR增加TR不变TR不变TR增加TR减少表6.2%∆Q%∆P%∆Q=%∆P%∆Q%∆P6-7©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.影响需求价格弹性的因素替代品的可获性~一种商品的替代品越多越容易获得，该商品的弹性越大占消费预算的份额~花费在某种商品上的支出占消费预算的比重越大，该商品就越有弹性调整的时期（调整需要的时间）~对于价格变动，消费者调整的时间越长,需求的弹性越大6-8©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.需求价格弹性计算价格弹性可以通过需求曲线的斜率(Q/P)乘以价格与数量之比(P/Q)来计算QEP100100QQPPQPPQ6-9©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.价格弹性可以在需求曲线的一个区间（或弧）上计算，也可以在需求曲线的特定点上计算~如果价格的变化相对较小，通常使用点弹性~如果价格变化在需求曲线上是一段较长的弧线，弧弹性比点弹性更合适需求价格弹性计算6-10©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.弧弹性的计算在计算需求曲线上某个区间的需求弹性时，利用弧弹性公式平均值平均值QPPQE6-11©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.点弹性的计算当计算需求曲线上某个点的弹性时,用该点上的斜率(Q/P）乘以该点的P/Q点弹性的计算方法取决于需求曲线是一条直线还是一条曲线6-12©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.线性需求时的点弹性•已知𝑸=𝒂+𝒃𝑷+𝒄𝑴+𝒅𝑷𝑹,令收入和相关产品的价格非别为特定的𝑴和𝑷𝑹•将需求函数表示为𝑸=𝒂′+𝒃𝑷,其中𝒂′=𝒂+𝒄𝑴+𝒅𝑷𝑹，斜率参数为𝒃=∆𝑸∕∆𝑷6-13©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.需求价格弹性可以通过下面两个等式中的任意一个得到线性需求时的点弹性PPEbEQPAor其中P和Q分别为该点的价格和数量；A(=–a′∕b)是需求的价格截距6-14©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwarded,distributed,orpostedonawebsite,inwholeorpart.点价格弹性可以通过下面两个等式中的任意一个得到需求为曲线时的点弹性QPPEPQPA其中∆Q∕∆P是需求曲线在该点的斜率,P和Q分别是该点的价格和需求数量,而A是该点切线延长到价格轴的价格截距6-15©2016byMcGraw-HillEducation.Thisisproprietarymaterialsolelyforauthorizedinstructoruse.Notauthorizedforsaleordistributioninanymanner.Thisdocumentmaynotbecopied,scanned,duplicated,forwar