微观经济学 双语课件 第4章 消费者行为理论 CH4 Consumer Choice Theory.ppt

Consumer Choice TheoryChapter 4 Content4.1 Utility4.2 Cardinal Utility4.3 Ordinal UtilityA story:珍珠翡翠白玉汤明太祖朱元璋从前是个乞丐，传说他有次在路上饿晕，被好心人救回家中，用豆腐块、菠菜、剩米饭煮成汤给朱元璋吃。朱元璋食后，精神大振，问刚才吃的是什么，回答说“珍珠翡翠白玉汤”。后来，朱元璋当上了皇帝，尝尽了天下美味，突然就想起了“珍珠翡翠白玉汤”的美味，当即下令御厨做给他吃。谁知御厨照着皇上的描述做好了汤，朱元璋尝后，却觉得根本不对味。又传在八国联军侵华之时，慈禧太后被迫西逃，路上又累又饿，在一户平民家里歇脚。主人没有什么好吃的，就把小米拌上少量白面做成面颗粒，倒入菠菜豆腐汤内。慈禧太后吃着觉得非常美味，问及汤名，答曰“珍珠翡翠白玉汤”，慈禧太后龙颜大悦。后来慈禧太后回宫，专门派御厨学做此汤，没想到再次吃上时，却怎么也吃不出当初在荒郊村野的平民家里那个香味了。Thinking珍珠翡翠白玉汤的传说说明了什么道理？4.1 Utility4.1.1 Definition of UtilityUtilityThe benefit or satisfaction that a person gets from the consumption of a good or service（消费者在消费商品时所感受到的满足程度）Utility is peoples subjective feeling4.1.2 The theory of utilityCardinalUtilityOrdinalUtility4.2 Cardinal Utility（基数效用）4.2.1 Introduction of Cardinal Utilitye.g.The utility of a new cloth is 100 units,the utility of a steak is 50 units,then the total utility of this shopping is 150 unitsUtility generally increases as the quantity consumed of a good increase（效用是消费量的函数）U=f（Q1，Q2，Qn）Marginal Utility AnalysisCardinal utility:Utility can be expressed by cardinal number and directly measured and summed（效用可以用基数表示，可以直接计量并加总求和）4.2.2 Total Utility and Marginal UtilityTotal UtilityTotal Utility(TU):(TU):The total benefit that a person gets from the consumption of a good or service TU=f（Q）Marginal UtilityMarginal Utility(MU (MU/边际效用):):The change in total utility that results from a one-unit increase in the quantity of a good consumed MU=TU/Q,MU=dTU/dQ除了边际效用之外，后面我们还要用到其他很多“边际值”，每一个边际值都代表着对应总量的增量，即总量的某个影响因素变动1个单位时，引起总量变动了几个单位小贴士QuantityTUMU0001303025020360104600550-10The Relationship between TU and MU（重要！总效用和边际效用的关系）TUQTUMUQWhen MU 0,TU;MUPPWhen MU (MUy/Py),buy more X and less Y,and vice verse(when all the budget has been spent)Application:Finding the Demand CurveDemand Price:The maximum price that a consumer is willing to pay for a given quantity of a good during a specified period (需求价格：消费者在一定时期内对一定量的某种商品所愿意支付的最高价格)Demand price depends on marginal utility:MU,Demand price Utility-maximizing rule for only one good:MUMU/P=/P=QMUMU=2=2P P13015220103105400QPQ=f（P）Demand PriceActual PriceConsumer Surplus:The maximum price that people are willing to pay for another unit of a good minus the price paid for it （消费者愿意支付的价格 实际支付的价格）P0Q0Application:Consumer Surplus（消费者剩余）Q1P1Exercise an Homework1、当总效用曲线达到顶点时，（）A、边际效用为最大值 B、边际效用为零C、边际效用为正 D、边际效用为负2、消费者剩余是（）A、消费过剩的商品B、消费者得到的总效用C、消费者买商品所得到的总效用减去支出的货币的总效用D、支出的货币的总效用3、已知消费者收入为100元，商品X的价格是10元，商品Y的价格是3元。假定他打算购买7单位X和10单位Y，此时X和Y的边际效用分别是50和18，如要获得最大效用，他应该（）A、停止购买B、减少X的购买量，增加Y的购买量C、增加X的购买量，减少Y的购买量D、同时增加X和Y的购买量4、消费者剩余是消费者的（）A、实际所得 B、主观感受C、没有购买的部分 D、消费剩余的部分5、钻石用处极小但价格昂贵，而生活中必不可少的水却价格便宜，请用边际效用的概念予以解释4.3 Ordinal Utility（序数效用）4.3.1 Introduction of Ordinal Utilitye.g.Consumer can not calculate the utility of a cloth or a steak by a certain number,but can accurately judge which one he prefersIndifference Curve AnalysisUtility is a psychological phenomenon,it can not be measured or summed up,we can only show the level of satisfaction with the order（效用作为一种心理现象无法计量，也不能加总求和，只能表示出满足程度的高低与顺序）4.3.2 Indifference Curves（无差异曲线）Assumptions for preference（关于偏好的假设）CompletenessTransferabilityUnsaturationConsumer can always compare and arrange all the different combinations of goodsThe preference:A B,and B C,then there must be A CConsumer always prefer the combinations that contain more goods to those that contain less goods完全性可传递性非饱和性Indifference Curve（无差异曲线）A line that shows combinations of goods among which a consumer is indifferent(that means the consumer like all the combinations equally)（无差异曲线表示消费者偏好相同的两种商品的所有组合）YXIOn the same curve,the utility of each combination equals the others（线上任何一点X与Y的不同组合，给消费者所带来的效用相同）Negative SlopeCan not intersectPrefer the right oneThe indifference curve is downward-slopingThe quantity consumed of one good must increase while the quantity consumed of the other one decreasing so that the total utility can remain the sameThere are countless indifference curves on the map,each one represent a different utility,and the farther away from the origin,the greater the utility isThe indifference curves on the same map are parallel to each other,otherwise it will conflict with the aboveFeatures of the Indifference CurveConvex to the originThe absolute value of slope is diminishing （斜率的绝对值递减）斜率为负同一平面上越靠右的曲线代表的效用越大任意两条不相交凸向原点Marginal Rate of Substitution(MRS)The rate at which a person will give up good Y(the good measured on the y-axis)to get more of good X(the good measured on the x-axis)and at the same time remain on the same indifference curve（在维持效用水平不变的前提下，消费者增加一单位商品X的消费量时所需放弃的商品Y的消费量）Absolute value of the slope of a certain point on the indifference curve（边际替代率是无差异曲线上某个点的斜率的绝对值）Marginal Rate of Substitution(MRS)An important relationship:Diminishing marginal rate of substitution（边际替代率递减）With a continuous increase in the quantity consumed of good X,the quantity of good Y that the consumer should give up to get one more unit of X is decreasing(remain on the same indifference curve)（在维持效用水平不变的前提下，随着商品X的消费量连续增加，消费者为得到每一单位的商品X所需要放弃的商品Y的消费量是递减的）4.3.3 Consumption Possibilities （消费可能性）The Budget Line The Budget Line（预算线）:A line that describes the limits to consumption choices which depends on a consumers budget and the prices of goodsPoint A:Spend all the budget on X（全买X）Point B:Spend all the budget on Y （全买Y）Point C:Can afford and have some unspent budgetPoint D:Can not affordEach point on the budget line represent a different combination of two goods and the cost of each combination equals to each other（购买曲线上每个点所花的钱相等）Y0ABXSlope:-PX/PYCDChanges in PricesYXXYPrice of X fallsPrice of X risesPrice of Y fallsPrice of Y remain the samePrice of Y risesPrice of X remain the samePrices remain the sameBudget，Budget Line Budget，Budget Line Change in the BudgetThe budget remain the sameDecreases of prices with proportion shift the budget line rightwardIncreases of prices with proportion shift the budget line rightward4.3.4 Consumer Equilibrium（消费者均衡）A&B:less utility,unspent budgetD:large utility but cant affordE(point of contact 切点):best affordable pointp Buy the affordable quantities of goods （钱花光）pAs well off as possible （获得最大满足）The consumers goal:Allocating the budget in a way to get onto the highest attainable indifference curve（尽量达到更高的无差异曲线）MRSXY=PX/PY(Equal slope at the point of contact)YXIEConsumer EquilibriumABD4.3.5 Substitution Effects and Income EffectsThe influences on the price of demand fall into two groups:pSubstitution effectspIncome effectsRelative PricepThe price of one good in terms of another goodpIt equals the price of one good divided by the price of another goodpThe absolute value of the slope of budget line is the relative price4.3.5 Substitution Effects and Income EffectsSubstitution EffectsThe effect of the relative price changeWhen the price of good X falls,the relative price of good X and good Y changes,X turns to be cheaper and Y becomes more expensive,so the consumer will choose a new combination which contains more X and less YIncome EffectsThe effect due to income having been freed upWhen the price of good X falls,the consumer can afford more X while the budget remains the same,it looks like the income increase5、替代效应和收入效应p 价格引起需求量变化价格引起需求量变化是替代效应和收入效应共同作用的结果是替代效应和收入效应共同作用的结果替代效应替代效应收入效应收入效应商品1降价，相对于商品2更便宜，消费者会增加商品1的购买量而减少商品2的购买量，即商品1替代了商品2商品1降价，相同货币的实际购买力增强，相当于实际收入水平增加，消费者会改变两种商品的购买量，以获得更大的效用总效应总效应价格变动引起相对价格变动，进而引起需求量变动价格变动引起相对价格变动，进而引起需求量变动不改变效用水平不改变效用水平价格变动引起实际收入水平变动，进而引起需求量价格变动引起实际收入水平变动，进而引起需求量变动变动效用水平会改变效用水平会改变Normal GoodsThe substitution:The quantity consumed of X increase when the price of X fallsThe income effect:The quantity consumed of X increase when the price of X fallsThe quantity consumed of X increase when the price of X fallsXCbX3FGU2cB0YaX1U1AX2Total EffectSubstitution EffectIncome Effect正常品的替代效应和收入效应替代效应和收入效应均使消费量与价格反方向变动，从而总效应必然使消费量与价格反方向变动，需求曲线向右下倾斜XCbX3FGU2cB0YaX1U1AX2补补偿偿预预算算线线总效应总效应替代效应替代效应收入效应收入效应Inferior GoodsY0XBABaX1bX3FGU1U2cX2Total EffectSubstitution EffectIncome EffectThe substitution effect:The quantity consumed of X increase when the price of X fallsThe income effect:The quantity consumed of X decrease when the price of X fallsThe substitution effect is greater than the income effectThe quantity consumed of X increase when the price of X falls一般低档品的替代效应和收入效应替代效应使消费量与价格反方向变动，收入效应使消费量与价格同方向变动，通常收入效应小于替代效应，故总效应使消费量与价格反方向变动，需求曲线向右下倾斜X2 0X1BABaX1 bX1 FGU1U2cX1 补补偿偿预预算算线线总效应总效应替代效应替代效应收入效应收入效应Giffen Goods0XYBABaX1 bX3 FGU1U2cX2Total EffectSubstitution EffectIncome EffectThe substitution effect:The quantity consumed of X increase when the price of X fallsThe income effect:The quantity consumed of X decrease when the price of X fallsThe income effect is greater than the substitution effectThe quantity consumed of X decrease when the price of X falls吉芬物品的替代效应和收入效应替代效应使消费量与价格反方向变动，收入效应使消费量与价格同方向变动，但收入效应的作用大于替代效应，故总效应使消费量与价格同方向变动，需求曲线向右上倾斜0X1X2 BABaX1 bX1 FGU1U2cX1 补补偿偿预预算算线线总效应总效应收入效应收入效应替代效应替代效应Exercise&Homework1、一个无差异曲线图可能包括无数条无差异曲线，这是因为（）A、人的欲望是无限的 B、消费者人数是无限的C、收入有时高有时低 D、商品的数量是无限的2、预算线的位置和斜率取决于（）A、消费者收入 B、消费者收入和商品价格C、消费者偏好 D、以上三者3、无差异曲线上任一点的商品X和Y的边际替代率等于它们的（）A、数量之比 B、边际效用之比C、价格之比 D、边际成本之比4、商品X和Y的价格以及消费者收入都按统一比率同方向变化，则预算线（）A、向左下方平移 B、向右上方平移C、向左下方或右上方平移 D、不移动5、在消费均衡点以上的无差异曲线的斜率（）A、大于预算线的斜率 B、小于预算线的斜率C、等于预算线的斜率 D、以上三种均有可能6、其他条件不变，某种商品（非吉芬商品）的价格下降，根据效用最大化原则，消费者会（）这种商品的购买A、增加 B、减少 C、不改变 D、增加或减少7、假定X、Y的价格PX、PY已定，当MRSXYPX/PY时，消费者为达到最大满足，他会（）A、增购X，减少Y B、减少X，增购YC、同时增购X和Y D、同时减少X和Y8、正常品的需求价格弹性为负，劣等品的需求价格弹性可能为负、为零或为正，请用替代效应和收入效应解释这种现象。Thanks！