弹性(Elasticity)3030.ppt

弹性(Elasticity) . . . … allows us to analyze supply and demand with greater precision. 使得我们能够以更大的精确性来分析供给与需求 … is a measure of how much buyers and sellers respond to changes in market conditions 它是一种对买方和卖方就市场条件的变化作出反应之程度的测度。  THE ELASTICITY OF DEMAND需求弹性 The price elasticity of demand is a measure of how much the quantity demanded of a good responds to a change in the price of that good. 需求的价格弹性是对某一商品需求数量就其商品价格变化作出的反应程度的测度。 When we talk about elasticity, that responsiveness is always measured in percentage terms. 当我们谈及弹性时，反应程度总是以百分比的形式予以测度的。 Specifically, the price elasticity of demand is the percentage change in quantity demanded due to a percentage change in the price. 具体说来，需求的价格弹性就是价格百分比的变化所引起的需求数量百分比的变化。 The Price Elasticity of Demand and Its Determinants需求的价格弹性及其决定因子 Availability of Close Substitutes 相近替代品的可获得性 Necessities versus Luxuries 必需品对奢侈品 Definition of the Market 市场的定义 Time Horizon 时间框架 The Price Elasticity of Demand and Its Determinants需求的价格弹性及其决定因子 Demand tends to be more elastic: 需求倾向于更加具有弹性（在以下情况下) the larger the number of close substitutes. 相近替代品的数量越大 if the good is a luxury. 如果该商品是一种奢侈品 the more narrowly defined the market. 市场的定义更加狭窄 the longer the time period. 时期跨度更长 Computing the Price Elasticity of Demand计算需求的价格弹性 The price elasticity of demand is computed as the percentage change in the quantity demanded divided by the percentage change in price. 需求的价格弹性是通过需求数量变化的百分比除以价格变化的百分比来计算的。 Computing the Price Elasticity of Demand计算需求的价格弹性 Example: If the price of an ice cream cone increases from $2.00 to $2.20 and the amount you buy falls from 10 to 8 cones, then your elasticity of demand would be calculated as: 范例：如果冰激凌蛋卷的价格从2美圆增加到2.2美圆，你购买的数量从10个下降到8个，那么你的需求弹性就可以这样计算： The Midpoint Method: A Better Way to Calculate Percentage Changes and Elasticities中点法：计算百分比变化和弹性的更好方式 The midpoint formula is preferable when calculating the price elasticity of demand because it gives the same answer regardless of the direction of the price change. 在计算需求的