chapter 5

# chapter 5 - Imagine that some event drives up the price of...

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Imagine that some event drives up the price of gasoline in the United States. It could be a war in the Middle East that disrupts the world supply of oil, a booming Chinese economy that boosts the world demand for oil, or a new tax on gasoline passed by Congress. How would U.S. consumers respond to the higher price? It is easy to answer this question in broad fashion: Consumers would buy less. That is simply the law of demand we learned in the previous chapter. But you might want a precise answer. By how much would consumption of gasoline fall? This question can be answered using a concept called elasticity, which we develop in this chapter. Elasticity is a measure of how much buyers and sellers respond to changes in market conditions. When studying how some event or policy affects a market, we can discuss not only the direction of the effects but their magnitude as well. Elasticity is useful in many applications, as we will see toward the end of this chapter. Before proceeding, however, you might be curious about the answer to the gasoline question. Many studies have examined consumers' response to gasoline prices, and they typically find that the quantity demanded responds more in the long run than it does in the short run. A 10 percent increase in gasoline prices reduces gasoline consumption by about 2.5 percent after a year and about 6 percent after five years. About half of the long-run reduction in quantity demanded arises because people drive less and half because they switch to more fuel-efficient cars. Both responses are reflected in the demand curve and its elasticity. 5-1 The Elasticity of Demand When we introduced demand in Chapter 4, we noted that consumers usually buy more of a good when its price is lower, when their incomes are higher, when the prices of substitutes for the good are higher, or when the prices of complements of the good are lower. Our discussion of demand was qualitative, not quantitative. That is, we discussed the direction in which quantity demanded moves but not the size of the change. To measure how much consumers respond to changes in these variables, economists use the concept of elasticity. 5-1a The Price Elasticity of Demand and Its Determinants The law of demand states that a fall in the price of a good raises the quantity demanded. The price elasticity of demand measures how much the quantity demanded responds to a change in price. Demand for a good is said to be elastic if the quantity demanded responds substantially to changes in the price. Demand is said to be inelastic if the quantity demanded responds only slightly to changes in the price. The price elasticity of demand for any good measures how willing consumers are to buy less of the good as its price rises. Thus, the elasticity reflects the many economic, social, and psychological forces that shape consumer preferences. Based on experience, however, we can state some general rules about what determines the price elasticity of demand. Availability of Close Substitutes

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## This note was uploaded on 07/14/2011 for the course ECO 1001 taught by Professor Barcia during the Spring '08 term at CUNY Baruch.

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chapter 5 - Imagine that some event drives up the price of...

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