Microeconomics: Theory and Applications with Calculus, 4e

2.5 Elasticities

It is convenient to be able to summarize the responsiveness of one variable to a change in another variable using a summary statistic. In our last example, we wanted to know whether an increase in the price of a product causes a large or a small change in the quantity demanded (that is, whether the demand curve is relatively vertical or relatively horizontal at the current price). We can use summary statistics of the responsiveness of the quantity demanded and the quantity supplied to determine comparative statics properties of the equilibrium. Often, we have reasonable estimates of these summary statistics and can use them to predict what will happen to the equilibrium in a market—that is, to make comparative statics predictions. ...