曼昆经济学原理课件(5章).ppt

弹性及其应用 5 本章我们将探索这些问题的答案： 什么是弹性？弹性能帮助我们理解什么问题？ 什么是需求价格弹性？它与需求曲线有什么联系？它与收益与支出又有什么联系？ 什么是供给价格弹性？它与供给曲线有什么联系？ 什么是需求收入弹性与需求的交叉价格弹性？ 弹性有何应用？ 主动学习 1 弹性与支出/收益 A. 药店将胰岛素的价格提高10%，对胰岛素的总支出会增加还是减少？ B. 作为价格战的结果，游轮价格下降了20%。游轮制造公司的收益会增加还是下降？ 主动学习 1 参考答案 主动学习 1 参考答案 主动学习 2 弹性与均衡的改变 主动学习 2 参考答案 主动学习 2 参考答案 内容提要 弹性衡量需求量或供给量对其一个影响因素变动的反应程度 需求价格弹性衡量需求量对价格变动的反应程度。如果弹性小于1，需求缺乏弹性；如果大于1，需求富有弹性 对于缺乏弹性的需求曲线，其总收益随着价格的上升而增加。对于富有弹性的需求曲线，其总收益随着价格的上升而减少 内容提要 如果某种物品没有相近的替代品，是必需品而不是奢侈品，市场范围大，或者是在短期内，那么，这种物品就更倾向于缺乏弹性 供给价格弹性衡量的是供给量对价格变动的反应程度。如果弹性小于1，供给缺乏弹性。如果弹性大于1，供给富有弹性 供给价格弹性在长期中比在短期中更富有弹性 内容提要 需求收入弹性衡量的是需求量对消费者收入变动的反应程度 需求的交叉价格弹性衡量一种物品需求量对另一种物品价格变动的反应程度 * This slide is a convenience for your students, and replicates a similar table from the text.  If you’re pressed for time, it is probably safe to omit this slide from your presentation. * Economists classify demand curves according to their elasticity. The next 5 slides present the five different classifications, from least to most elastic. * If Q doesn’t change, then the percentage change in Q equals zero, and thus elasticity equals zero. It is hard to think of a good for which the price elasticity of demand is literally zero. Take insulin, for example. A sufficiently large price increase would probably reduce demand for insulin a little, particularly among people with very low incomes and no health insurance. However, if elasticity is very close to zero, then the demand curve is almost vertical. In such cases, the convenience of modeling demand as perfectly inelastic probably outweighs the cost of being slightly inaccurate. * An example: Student demand for textbooks that their professors have required for their courses. Here, it’s a little more clear that elasticity would be small, but not zero. At a high enough price, some students will not buy their books, but instead will share with a friend, or try to find them in the library, or just take copious notes in class. Another example: Gasoline