曼昆经济学原理(微观经济学)笔记

曼昆经济学原理(微观经济学)笔记

曼昆《经济学原理——微观经济学》笔记目录一、经济学的十大原理：····································································································································1二、循环流量图（资本循环、要素循环）······································································································1三、实证分析与规范分析····································································································································1四、绝对优势与比较优势····································································································································1五、几种价格弹性与商品关系···························································································································2六、需求价格弹性················································································································································2七、政府限价对市场的影响·······························································································································3八、税收归宿（TAXINCIDENCE）·····················································································································3九、曼昆的市场有效（EFFICIENT）·················································································································3十、税收的代价····················································································································································4十一、国际贸易与关税········································································································································4十二、公共部门——外部性·······························································································································5十三、公共物品和公有资源·······························································································································7十四、市场结构····················································································································································7十五、寡头与古诺模型········································································································································8十六、生产要素市场（劳动力市场）···············································································································8十七、减少贫困的政策········································································································································8十八、无差异曲线与收入替代效应（斯勒茨基方程）·················································································9十九、博弈论·······················································································································································10二十、微观经济学前沿······································································································································11\n一、经济学的十大原理：①人们面临权衡的取舍。②某种东西的成本是为了取得它所放弃的东西。（也就是机会成本）③理性人考虑边际量。（理性人通过比较边际收益与边际成本来做出选择）④人们会对激励做出反应。⑤贸易能使每个人都获得好处。⑥市场通常是组织经济活动的一种好方法。⑦政府有时可以改善市场结果。（市场失灵时存在外部性或市场力量）⑧一国的生活水平取决于它生产物品与劳务的能力。⑨当政府发行了过多的货币时，物价上升。⑩社会面临通货膨胀与失业之间的短期权衡取舍。二、循环流量图（资本循环、要素循环）收支益出产品市场出购售买企家业庭购出买售要素市场收入工资、租金、利润三、实证分析与规范分析实证分析是描述性的，企图描述世界是什么的观点。规范分析是命令性的，企业描述世界应该是什么。例子：（实证分析）最低工资法引起了失业。（规范分析）政府应提高最低工资。四、绝对优势与比较优势案例：假设中国工人每小时能生产50个烧饼或4件毛衣；英国工人每小时能生产40个烧饼或2件毛衣。烧饼毛衣名称产量机会成本产量机会成本中国500.08412.5英国400.052201\n从上图可以看出，中国在生产烧饼和毛衣上都有绝对优势。中国在生产毛衣的机会成本小于英国，在生产毛衣上有比较优势；英国在生产烧饼的机会成本小于中国，在生产烧饼上有比较优势。五、几种价格弹性与商品关系1、【收入与需求数量的关系】正常物品：收入增加，需求数量增加。低档物品：收入减少，需求数量增加。2、【价格与需求数量的关系】普通商品：价格下降，需求数量增加。吉芬物品：价格上涨，需求数量增加。3、【价格与需求数量的关系】（弹性=物品1需求数量的变化百分比/物品2的价格变化百分比）替代品：弹性为正互补品：弹性为负六、需求价格弹性（Q-Q)/[(Q+Q)/2]2121需求价格弹性（中点法）=（P-P)/[(P+P)/2]2121价格有弹性●单位弹性无弹性MR=0数量1MR=-pq()[1]e边际收益e>101<MCP>MC能生产福利最大化吗？能不能不能长期企业数量很多很多一个长期中能进入吗？能能不能长期中能赚到经济利润吗？不能不能能关系式P=AR=MR=MC=ATCP=ATC>MR=MCP>MR=MC>ATC图1：完全竞争图2：垄断竞争图3：垄断PPPMCMCMCATCATCATCPPPMR需求需求MRMRQQQQQ1Q2Q完全竞争：垄断竞争：垄断：P=AR=MR最大化条件：MR=MC最大化条件：MR=MCMC=AVC短期（营业与否）利润为0利润=（P-ATC）QMC=ATC长期（退出与否）P=ATC>MR=MC，市场无效率无效损失=0.5*（Q2-Q1）*（P-ATC）最大化条件：MR=MC（市场有效率的点为ATC的最P>MR=MC>ATC利润=（P-ATC）Q低点，即P=ATC。）长期均衡时，利润为0。P=AR=MR=MC=ATC7\n十五、寡头与古诺模型1、判断标准：只有一家企业，市场就是垄断只有几家企业，市场就是寡头有很多家企业，出售的产品有差别，则是垄断竞争出售的产品相同，则是完全竞争2、Q垄断P寡头>P完全竞争3、古诺模型的推导十六、生产要素市场（劳动力市场）1、一个竞争性的、利润最大化的企业雇佣的工人数要达到劳动的边际产量值等于工资的那一点，边际产量曲线就是劳动力需求曲线。P*MPL(边际产量)=W=边际产量值，P=W/MPL=边际产量值/MPL=MC（如图1所示）图1图2边际产量值工资（劳动价格）供给市场均衡工资工资需求均衡工人数量劳动数量就业量图2结论：改变劳动供求的任何事件都必定使均衡工资和边际产量值等量变动，因为这两个量总是相等的。2、新古典分配理论：每种生产要素所得到的报酬量取决于该要素的供给与需求，需求又取决于某种要素的边际生产率。在均衡时，每种生产要素赚到了它在物品与劳务生产中的边际贡献的价值。3、人力资本理论4、信号理论5、效率工资理论十七、减少贫困的政策1、最低工资法（支持者：最低工资作为帮助那些有工作的穷人，而政府又不花钱。）（反对者:最低工资看成是对它提供帮助的人的一种伤害，并且最低8\n工资可能使某些人的境况变得更差，青年人失业的机率更高。）2、福利：政府补贴收入。（反对者：激励了人们变成“需要帮助者”。）3、负所得税：向高收入家庭征收并给低收入家庭转移支付。4、食物转移支付：直接向穷人提供物品与劳务。十八、无差异曲线与收入替代效应（斯勒茨基方程）1、无差异曲线及其特点（图形参见附件）（1）高无差异曲线偏好大于低的无差异曲线。（2）向右下方倾斜。（3）不相交。（4）凸向原点。2、斯勒茨基方程Q2BèA，收入效应CèB，替代效应收入效应大于替代效应替代效用：由于价格的变化而变化△X=-xdd(p*,p,m)x(p,,)pms122121收入效用：由于收入的变化而变化△BCAQ1X=xdd(p**,,pm)-x(p,pm,)m121122总效应：△X+△X=xd(p*,,)pm-xd(p,pm,)sm121121P（注：与价格变动的方向）替代效应收入效应正常商品（P↓，Q↑）相反相反低档商品（P↓，Q↓）相反相同需求曲线Q13、需求法则如果一种商品的需求随着收入的增加而增加，那么，这种商品的需求一定会随着价格的上升而下降。（说明为正常商品）4、完全互补：替代效应为0.完全替代：收入效应为0.拟线性偏好：收入效应为0.（有实际收入的变化，但没有导致x的需求增加）19\n5、两种特例：课税退税、实时定价十九、博弈论参与人B1、占优策略左右参与人上1,20,1A下2,11,0对A而言，选择下大于上；对B而言，选择左大于右。即在某个博弈中，每个参与人都有一个占优策略，则这个占优策略组合就是博弈均衡的结果。即A选上，B选左，（1,2）为占优策略均衡的结果。参与人B2、纳什均衡左右参与人上2,10,0A下0,01,2给定A的选择，B的选择也是最优的；并且给定B的选择，A的选择也是最优的。则称为纳什均衡。例：A选择上，则B选择左（2,1）；B选择左，则A选择上（2,1）。纳什均衡存在的问题：（1）存在一个以上的纳什均衡（2,1），（1,2）（2）不存在（纯策略）纳什均衡。即如下图所示：A选上，则B选左（0,0）；B选左，则A选下（1,0）。参与人B图3左右参与人上0,00,-1A下1,0-1,33、混合纳什均衡如果图3中A有75%选上，25%选下；B有50%选左，50%选右。若B选左，则A会选上（0,0）；反之，A选上，B会选左（0,0）。则（0,0）为混合纳什均衡。参与人B4、囚徒困境坦白抵赖参与人坦白-3，-30，-6A抵赖-6,0-1，-1囚徒困境模型表明：通常情况下，都选择坦白（-3，-3）；但这不是帕累托有效率的，有效率的选择是都抵赖（-1，-1）。10\n5、序贯博弈：一个参与人首先采取行动，另一个参与人再作出反应。参与人B5、序贯博弈左右参与人上1,91，9A下0,02，1左（1,9）上è参与人B选择右（1,9）参与人A选择左（0,0）下è参与人B选择右（2,1）通常情况下：参与人A选择下，则B理智的选择右，A达到了利益最大化，但B不是，没有达到帕累托最优。在这种情况下，B会威胁A：如果A选择下，B将选择左（0,0）。如果这种威胁有用，则B的境况会变好，并且达到帕累托有效。6、遏制进入的博弈（针对垄断、寡头）斗争（1,9）不进入è在位者选择不斗争（1,9）进入者选择斗争（0,2）进入è在位者选择不斗争（2,1）结论：从图上可以看出，不进入是有效率的，并且不进入也是明智的。二十、微观经济学前沿1、不对称信息道德风向、逆向选择、为传递私人信息发信号2、政治经济学康多赛悖论、阿罗不可能性定理3、行为经济学（1）人并非总是理性的。因为A、人们过分自信；B、人们过分重视从现实生活中观察到的细枝末节；C、人们不愿意改变自己的观点。（2）人关注公正。（3）人有时是矛盾的。11\n完全替代品完全互补品柯布—道格拉斯拟线性偏好厌恶品中性商品无差xxxx2222xx异22x2曲线x1x1x1x1x1x1效用：aa1-效用：效用u(x1,)x2=+ax12bx效用：u(x1,)x2=xx12u(x,x)=min(ax,)bxu(x,x)=k=+v()xx12121212最优选择：（如下图）最优选择：（如下图）最优选择：（如下图）（效用对商品2是线性效m/p1pp12p2最优x2xx选x222择xxxx1111完全替代品完全互补品柯布—道格拉斯拟线性偏好厌恶品中性商品12\n收入xxxx提2222供pp<12曲线xxxx1111恩格尔mmmm曲恩格尔曲线恩格尔曲线恩格尔曲线线斜率=p1斜率=pp12+斜率=pa1/xxxx1111需求PP曲线x1x113