微观经济学chapter解析.pptVIP

* 36 * * * * * * * 12 * 13 * 14 * 22 * 34 * 44 * 49 * 50 * 63 * * * 弹性作用：价格或其他条件变化时候供需变化的确切数值，用于预测；借由弹性变化倒推出供需曲线 弹性度量一个变量对另一个变量的敏感性 注意弹性是百分比的变化的比值 百分比的变化是变化量除以其初始值 * * 一般，需求线向下倾斜，所以需求价格弹性是负数 需求富有弹性，需求下跌百分比大于价格上涨百分比，需求变化大于价格变化；无弹性是需求变化小于价格变化 * 用途越广，可替代性越强；对消费者生活越重要，弹性越小；支出比重越大，越有倾向寻找替代品，价格弹性越大；调节需求量的时间越长，偏好可能发生变化，可以寻找更多可替代品，则弹性越大，即长期弹性大于短期弹性。 * 76 * 76 * 富有弹性的商品比较适合薄利多销。 手机上市之初，可替代性很小，需求价格弹性非常小，此时，高价高利，而上市一段时间后，可替代性增强，则需求价格弹性较高，因此薄利多销。 * 79 * * * * 81 * * * * 84 * 一般所指的弹性为点弹性 * 经济学中的暂时、短期长期。并不只是时间的概念。暂时：供给不可变。短期：至少一种投入要素不变；长期：所有投入要素可变。 实际上不管是偏好还是存量的影响，还是涉及到替代品的问题。存量大，对汽油需求高，短期难以找到汽油的替代品。但长期则可以寻找节油技术的车辆。 * 89 (b) Automobiles: Short-Run and Long-Run Demand Curves The opposite is true for automobile demand. If price increases, consumers initially defer buying new cars; thus annual quantity demanded falls sharply. In the longer run, however, old cars wear out and must be replaced; thus annual quantity demanded picks up. Demand, therefore, is less elastic in the long run than in the short run. Demand and Durability Short-Run Versus Long-Run Elasticities Short-Run Versus Long-Run Elasticities Income Elasticities Income elasticities also differ from the short run to the long run. For most goods and services—foods, beverages, fuel, entertainment, etc.— the income elasticity of demand is larger in the long run than in the short run. For a durable good, the opposite is true. The short-run income elasticity of demand will be much larger than the long-run elasticity. Demand TABLE 2.1 Demand for Gasoline Number of Years Allowed to Pass Following a Price or Income Change Elasticity 1 2 3 5 10 Price ?0.2 ?0.3 ?0.4 ?0.5 ?0.8 Income 0.2 0.4 0.5 0.6 1.0 TABLE 2.2 Demand for Automobiles Number of Years Allowed to Pass Following a Price or Income Change Elasticity 1 2 3 5 10 Price ?1.2 ?0.9 ?0.8 ?0.6