微观经济学原理 1 吉林大学商学院 刁莉男 diaoln@jlu.edu.cn Dear Colleague, Thank you for using the Premium PowerPoints for Mankiw’s Principles of Economics. I update these approximately once per year, to update the data, fix any typos, and incorporate the best suggestions from users like yourself. If you have any suggestions, corrections, or feedback, please email me at rcronovich@carthage.edu. Check the textbook’s website to make sure you’re always using the most recent version. In this area (the “notes” section), I occasionally include notes that are visible only to you and will not display during your presentation in class. In slides with data tables or charts, the notes area provides the source information (often a URL or web address to the original data). In other slides, the notes area provides information that might be helpful when teaching this material, particularly for new instructors and grad assistant teachers. For chapter 1, most instructors try to cover this chapter in a single class session (especially those that are teaching the second of a two-semester sequence). If you are teaching a “principles of microeconomics” course, you might consider skipping Principles 8-10, which deal with macroeconomics. Near the end of the chapter are four slides titled “FYI: How to Read Your Textbook.” In the notes section of these slides, I describe an in-class activity that teaches effective reading skills to students.

参考书 经济学原理-微观经济学分册，第6版，曼昆著(N. Gregory Mankiw)，北京大学出版社。 课件下载： http://cc.jlu.edu.cn/micro.html 经济学十大原理

1. 什么是经济学？ 经济(economy)一词来源于希腊语oikonomos，意思是“管理家庭的人”。 Alfred Marshall：经济学是一门研究人类一般生活事务的学问。 经济学十大原理

1. 经济学研究什么问题 稀缺性(scarcity): 社会资源的有限性 1. 经济学研究什么问题 稀缺性(scarcity): 社会资源的有限性 经济学(economics): 研究社会如何管理自己的稀缺资源, 比如： 人们决定购买什么, 工作多长时间，储蓄多少， 消费多少 企业决定生产多少，雇佣多少工人 社会决定如何在国防，消费物品，环境保护和其他需求之间分配资源 You might want to elaborate a bit on some of the points made here. Some examples: “How do people decide how much to work?” Time is scarce resource – there’s just not enough time to do everything we’d like to do. How do we decide how much of our time to spend working? There’s a tradeoff: the more time we spend working, the higher our income, and therefore the more stuff we can buy. But, the more time we spend working, the less time we have for leisure – hanging out with friends, going hiking, watching movies, etc. (You might want to ask your students how THEY decide how much time to spend working. Some will say it depends on how many classes they are taking, or the time requirements of the available jobs. But probably at least a few will say the wage – the higher the wage, the more worthwhile to work.) “How do firms decide what kind of labor to hire?” Firms can hire unskilled or skilled workers. The skilled workers are more productive, but cost more than the unskilled workers. “How do firms decide how much to produce?” Ask your students, and see if any of them say “it depends on the price of the product they sell.” (Probably some will say “it depends on whether there’s a lot of demand for the product”. To which you might respond “and if there’s a lot of demand for the product, what does that mean for the price that firms can get for the product?”) 经济学十大原理 3

1. 为什么要学习经济学？ 我们的生活与经济学息息相关。 有助于了解我们所生活的世界。 更好地理解经济政策的潜力和局限性。 经济学十大原理

第一章： 经济学十大原理 本章我们将探索这些问题的答案: 人们如何做出决策? 人们如何相互交易? 整体经济如何运行? 5

人们如何做出决策 Decision-making is at the heart of economics. The individual must decide how much to save for retirement, how much to spend on different goods and services, how many hours a week to work. The firm must decide how much to produce, what kind of labor to hire. Society as a whole must decide how much to spend on national defense (“guns”) versus how much to spend on consumer goods (“butter”). 6

2. 人们如何做出决策 原理一: 人们面临权衡取舍(trade-off) 天下没有免费的午餐！！ 所有决策都面临着权衡取舍。比如: 原理一: 人们面临权衡取舍(trade-off) 天下没有免费的午餐！！ 所有决策都面临着权衡取舍。比如: 学生的时间资源； 家庭收入； 社会：大炮和黄油、污染和生产。 经济学十大原理

2. 人们如何做出决策 原理一: 人们面临权衡取舍 社会面临一种重要的权衡取舍: 效率 vs. 平等 原理一: 人们面临权衡取舍 社会面临一种重要的权衡取舍: 效率 vs. 平等 效率(efficiency): 社会能从其稀缺资源中得到的最大利益 平等(equality): 经济成果在社会成员中平均分配 权衡取舍：为使社会更加平等, 需要在富人与穷人之间重新分配收入。但这会减少工作与生产的激励，并缩小经济“蛋糕”的规模 HEADS UP. The 5th edition uses “equality.” The fourth and earlier editions used “equity” here. You may want to elaborate verbally on the last bullet to insure that the point is clear. “Redistribute income from wealthy to poor” is accomplished through the progressive tax system, as well as social programs like food stamps and unemployment insurance that try to provide a safety net for people at the low end of the income distribution. “But this reduces the incentive to work” – the reward for working hard is a high income. Taxes reduce this reward, and therefore reduce the incentive to work hard. 经济学十大原理 8

原理二: 某种东西的成本是为了得到它所放弃的东西 2. 人们如何做出决策 原理二: 某种东西的成本是为了得到它所放弃的东西 人们做出决策时需要比较可供选择行动方案的成本与利益 任何一种东西的机会成本(opportunity cost)是为了得到这种东西所放弃的东西 这是人们做决策的相关成本 经济学十大原理

原理二:某种东西的成本是为了得到它所放弃的东西 2. 人们如何做出决策 原理二:某种东西的成本是为了得到它所放弃的东西 例如： 上一年大学的机会成本不仅仅是学费，书籍，住房和伙食的钱全部加起来，还包括由于没有工作而损失的工资 看一场电影的机会成本不仅是票价，还包括你呆在剧院的时间的价值 Here’s a fun tangent if you have the class time and are so inclined: Ask your students about the saying “The best things in life are free.” Ask them to name some of these things that supposedly are free. Ask them what “free” means in this context. The idea here is to get them to see that even things without an explicit monetary cost are not truly “free” because they have an opportunity cost. For example, when you ask them to name the “best things” that are “free,” they will respond with answers like love, sitting at the top of a mountain you just climbed and enjoying an awesome view, or maybe witnessing the joy of a child who has just been given a new toy. In each case, there is no explicit monetary cost, but there’s an opportunity cost. For example, a day spent climbing a mountain represents a day of foregone wages. And the fact that the mountain offers the incredible view probably means that land has been set aside for a national park that might otherwise have been used to produce industrial chemicals, or for a subdivision of million-dollar homes. With love, it’s less obvious, but if prodded enough, your students will be able to think of non-monetary costs associated with love. For example, you might not want to see the latest Ashton Kutcher film, you might think he’s the world’s worst actor. But your boyfriend/girlfriend/teenage daughter or other loved one is DYING to see it, they are BEGGING you to take them. So you take them. That’s true love, don’t you think? And it’s certainly not free. 经济学十大原理 10

原理二:某种东西的成本是为了得到它所放弃的东西 2. 人们如何做出决策 原理二:某种东西的成本是为了得到它所放弃的东西 思考题： 1、你正打算周末去做兼职，但你朋友让你去滑雪。去滑雪的真实成本是什么？现在假设你本来打算周六在图书馆学习，在这种情形下，去滑雪的成本是什么？ 2、现假设你买彩票赢了100元钱，可以选择将钱花掉或者存入银行，银行利率为5%。现在将这笔钱花掉的机会成本是多大？ 经济学十大原理

2. 人们如何做出决策 原理三: 理性人考虑边际量 边际变动： 理性人： 系统而有目的地尽最大努力实现其目标的人； 企业：利润最大化； 个体：实现最高水平的满足程度（效用最大化）。 边际变动： 对现有行动计划的微小增量调整； 通过比较成本与利益的边际变动(marginal change)来做出决策，即：边际收益和边际成本。 经济学十大原理

2. 人们如何做出决策 原理三: 理性人考虑边际量 例如: 原理三: 理性人考虑边际量 例如: 当一个大学生考虑是否要多上一年学时，他会比较学费加上损失的工资和多上一年学所增加的额外收入 当一个经理在考虑是否要增加产出时, 她会在增加的劳动力与原材料的成本和额外的收益之间进行比较 See the textbook for two classic examples: 1. The diamond-water paradox: water is essential for life but virtually free; diamonds are inessential but expensive. 2. The near-zero marginal cost of an airline taking an extra passenger when the flight isn’t full. 经济学十大原理 13

2. 人们如何做出决策 原理三: 理性人考虑边际量 原理三: 理性人考虑边际量 思考1：假设某飞机有200个座位，飞行一次成本为100,000万元。每个座位的飞行成本为500元。如果在飞机起飞前，还剩余10个座位，一个乘客愿意付300元买一张机票。航空公司是否应该将票卖给他？ 思考2：为什么水便宜而钻石那么昂贵？稀缺性和边际收益。 经济学十大原理

2. 人们如何做出决策 原理四: 人们会对激励做出反应 激励(incentive)：引起一个人做出某种行为的某种东西，诸如惩罚或奖励的预期 原理四: 人们会对激励做出反应 激励(incentive)：引起一个人做出某种行为的某种东西，诸如惩罚或奖励的预期 理性人会对激励做出反应 例如： 当汽油价格上涨时, 消费者会更多的购买混合动力汽车，更少购买耗油的越野车 当烟草税上升时，青少年吸烟人数会下降 经济学十大原理

2. 人们如何做出决策 原理四: 人们会对激励做出反应 思考题： 原理四: 人们会对激励做出反应 思考题： 社会保障系统为年龄超过65岁的老人提供收入。如果接受救济的某个老人决定去工作以争取部分收入，那么他从社会保障得到的钱数通常就会减少。 提供社会保障对人们在工作期间（年轻时）的储蓄激励有何影响？ 收入较高时保障金会下降，这对65岁以上老人的工作激励有何影响？ 经济学十大原理

人们如何相互交易 Whether we’re talking about the U.S. economy, or the local economy, the term “economy” simply means a group of people interacting with each other. These interactions play a critical role in the allocation of society’s scarce resources. For example, the interaction of buyers and sellers determines the prices of goods and the amounts produced and sold. These interactions are an important part of what economists study. 17

3. 人们如何相互交易 原理 5 :贸易可以使每个人的状况都变得更好 人们可以专门生产一种物品或劳务并用来交换其他物品或劳务，而不必自给自足 国家之间也能从贸易与专业化中受益 将他们生产的物品出口而得到一个更好的价格 从国外进口更便宜的物品而不用在国内自己生产 If each person had to grow his own food, make his own clothes, cut his own hair, we would have a world full of skinny, unfashionable poor people having bad hair days every day of the week. It’s far more efficient for each person to specialize in producing a good or service, and then exchanging it with other people for the things they produce. The statement “trade can make everyone better off” should not be hard to understand, if you think about it for a moment: Each of two parties would not voluntarily enter into an exchange if it made either of them worse off, now would they? The same principles apply at the national and international level: International trade allows countries to sell their exports abroad and get a higher price, and to buy things from abroad more cheaply than they could produce at home. In addition, trade gives a country’s consumers access to a greater variety of goods – including goods they might not be able to get at all. For example, U.S. consumers enjoy a variety of fresh produce year-round. This would not be possible without international trade. 经济学十大原理 18

原理 6 :市场通常是组织经济活动的一种好方法 3. 人们如何相互交易 原理 6 :市场通常是组织经济活动的一种好方法 市场: 大量的买者与卖者 (不必要在同一个地点) 市场经济：许多企业和家庭在物品和劳务市场上相互交易，通过他们的分散决策来配置资源的经济。 亚当.斯密在《国富论》（1776）中的著名观察结果： 家庭和企业仿佛被一只“看不见的手”所指引，在市场上相互交易，并增进整体经济的福利 A market economy is “decentralized,” meaning that there is no government committee that makes the decisions about what goods to produce and so forth. Instead, many households and firms make their own decisions: * Each of many households decides who to work for and what goods to buy. * Each of many firms decides whom to hire and what goods to produce. 经济学十大原理 19

原理 6 :市场通常是组织经济活动的一种好方法 3. 人们如何相互交易 原理 6 :市场通常是组织经济活动的一种好方法 “看不见的手”通过价格体系来发挥作用: 买者与卖者之间的相互作用决定市场价格 每个价格即反映了物品对于买者的价值，也反映了生产物品的成本 在许多情况下，价格引导自利的家庭与企业做出使社会经济福利最大化的决策 经济学十大原理

3. 人们如何相互交易 原理 7 :政府有时可以改善市场结果 政府的重要作用: 1、保护财产所有权 (property rights) (通过警察，法律)是指个体拥有并控制稀缺资源的能力。如果人们的财产存在很大的被侵犯的风险，那么他们便不愿意工作，生产，投资或者购买物品 [“Govt” is an abbreviation for government. Throughout all of the Premium PowerPoint chapters, I try to use abbreviations the way a thoughtful instructor would use them if writing on a chalkboard. If you prefer to spell the word out, just use your mouse to highlight “govt” and then type out the full word.] Two examples of the idea in the second bullet point: A restaurant won’t serve meals if customers do not pay before they leave. A music company won’t produce CDs if too many people avoid paying by making illegal copies. Many fledging market economies are struggling through the transition from central planning because they have not developed institutions that protect and enforce property rights. The British news magazine The Economist has lots of current examples of this. An older but still interesting example comes from a column that Mankiw wrote in the June 12, 2000 issue of Fortune magazine entitled “Ukraine: How Not To Run An Economy.” 经济学十大原理 21

3. 人们如何相互交易 原理 7 :政府有时可以改善市场结果 2、促进效率 市场失灵(market failure)：市场本身不能有效配置资源的情况 原因： 外部性(externality)：生产或消费一个物品影响到旁观者的福利（比如：污染） 市场势力(market power)：单个（或少数）买者或卖者有能显著影响市场价格的能力（比如，垄断） 经济学十大原理

3. 人们如何相互交易 原理 7 :政府有时可以改善市场结果 3、促进平等 政府可以改变市场结果以促进公平 如果经济福利的市场分配结果不是合意的，税收或福利政策能改变经济“蛋糕”的分配方式 经济学十大原理

3. 人们如何相互交易 原理 7 :政府有时可以改善市场结果 思考题： 解释下面每一项政府行为的出发点是更关注平等还是效率。如果是效率，分析可能涉及的市场失灵情形。 管制有线电视价格； 为某些穷人提供购买食品时可做钱使用的食品券； 在公共场所禁止吸烟； 将标准石油公司拆分成几家小公司； 对高收入人群征收较高的所得税； 颁布法律禁止酒后开车。 经济学十大原理

整体经济如何运行

原理 8 :一国的生活水平取决于它生产物品与劳务的能力 4. 整体经济如何运行 原理 8 :一国的生活水平取决于它生产物品与劳务的能力 各国不同时期生活水平的巨大差异： 发达国家的平均收入是发展中国家平均收入的十倍以上 今天美国的生活水平比100年以前大约增长了八倍 “Rich countries” refers to countries like the U.S., Japan, and Germany. “Poor countries” refers to countries like India, Indonesia, and Nigeria. 经济学十大原理 26

原理 8 ：一国的生活水平取决于它生产物品与劳务的能力 4. 整体经济如何运行 原理 8 ：一国的生活水平取决于它生产物品与劳务的能力 决定生活水平的最重要因素：生产力(productivity)，即每一单位劳动投入所生产的物品与劳务数量 生产力取决于设备，劳动者的技能以及可用的技术。 生产力是决定生活水平的主要决定因素，其它因素（比如，工会组织，国外的竞争）对于生活水平的影响远远小于生产力。 经济学十大原理

4. 整体经济如何运行 原理 9 :当政府发行了过多货币时，物价上升 通货膨胀(inflation)：物价总水平的上升。 长期而言，通货膨胀总是由于货币数量的过度增长而导致货币价值的下降所引起 政府创造货币的速度越快，通胀率越高 经济学十大原理

原理 10 :社会面临通货膨胀与失业之间的短期权衡取舍 4. 整体经济如何运行 原理 10 :社会面临通货膨胀与失业之间的短期权衡取舍 短期内（1-2年），许多经济政策朝相反的方向推动通货膨胀与失业 其它因素使这种权衡取舍不那么明显，但这种权衡取舍一直都存在 While the long-run effect of increasing the quantity of money is inflation, the short-run effects are more complicated - and controversial. However, most mainstream economists believe the following: An increase in the quantity of money causes spending to rise, which causes prices to rise, which induces firms to produce more goods and services, which requires that they hire more workers. Hence, in the short-run, increasing the quantity of money causes inflation to rise, but unemployment to fall. Of course, REDUCING the quantity of money would have the opposite effects (inflation would fall, while unemployment would rise) in the short run. Keep in mind, though, the lesson from Principle #9: In the long run, changing the quantity of money only affects inflation. We will learn in a later chapter what determines the rate of unemployment in the long run, and we will see that it has nothing to do with the quantity of money. The second bullet addresses the following point: In some decades, due to factors outside of the control of policymakers, inflation and unemployment are both high (e.g. 1970s) – or low (e.g. 1990s). Yet, given these other factors, policymakers can always reduce unemployment temporarily by creating more inflation, or vice versa. 经济学十大原理 29

内容提要 关于个人做出决策的基本结论是： 人们面临不同目标之间的权衡取舍 任何一种行为的成本可以用其所放弃的机会来衡量 理性人通过比较边际成本与边际利益做出决策 人们根据他们所面临的激励改变自己的行为 Each Premium PowerPoint chapter ends with a summary similar to the textbook’s chapter summaries. Many instructors do not cover these chapter summaries in class. 30

内容提要 关于人们之间相互交易的基本结论是： 贸易可以是互利的 市场通常是协调人们之间经济活动的一种好方法 通过纠正市场失灵或提高经济中的平等程度，政府可以潜在地改善市场结果 31

内容提要 关于整体经济的基本结论： 生产率是生活水平的最终根源 货币量的增长是通货膨胀的最终根源 社会面临着通货膨胀与失业之间的短期权衡取舍 32