理性消费者课件

1、,chapter:,10,Krugman/Wells Economics,2009 Worth Publishers,The Rational Consumer,How consumers choose to spend their income on goods and services Why consumers make choices by maximizing utility, a measure of satisfaction from consumption Why the principle of diminishing marginal utility applies to

2、the consumption of most goods and services How to use marginal analysis to find the optimal consumption bundle What income and substitution effects are,Opportunity Cost and Decisions,The utility of a consumer is a measure of the satisfaction the consumer derives from consumption of goods and service

3、s. An individuals consumption bundle is the collection of all the goods and services consumed by that individual. An individuals utility function gives the total utility generated by his or her consumption bundle. The unit of utility is a util.,Utility function,Marginal Utility Curve,7,9,8,6,5,4,3,2

4、,1,0,70,60,50,40,30,20,10,Total utility (utils),Quantity of clams,7,9,8,6,5,4,3,2,1,16,14,12,10,8,6,4,2,0,2,Marginal utility per clams (utils),Quantity of clams,(a),Cassies Utility Function,(,b,),Cassies Marginal Utility Curve,Cassies Total Utility and Marginal Utility,Cassies Total Utility and Marg

5、inal Utility,Cassies total utility depends on her consumption of fried clams. It increases until it reaches its maximum utility level of 64 utils at 8 clams consumed and decreases after that. The marginal utility curve slopes downward due to diminishing marginal utility; each additional clam gives C

6、assie less utility than the previous clam.,The Principle of Diminishing Marginal Utility,The marginal utility of a good or service is the change in total utility generated by consuming one additional unit of that good or service. The marginal utility curve shows how marginal utility depends on the q

7、uantity of a good or service consumed. The principle of diminishing marginal utility says that each successive unit of a good or service consumed adds less to total utility than the previous unit.,Budgets and Optimal Consumption,A budget constraint requires that the cost of a consumers consumption b

8、undle be no more than the consumers total income. A consumers consumption possibilities is the set of all consumption bundles that can be consumed given the consumers income and prevailing prices. A consumers budget line shows the consumption bundles available to a consumer who spends all of his or

9、her income.,1,0,2,3,4,5,10,8,6,4,2,A,B,C,D,E,F,Affordable consumption bundles that cost all of Sammys income,Sammys Budget Line, BL,Affordable consumption bundles,Unaffordable consumption bundles,Quantity of clams (pounds),Quantity of potatoes (pounds),The Budget Line,Sammys Utility from Consumption

10、,Optimal Consumption Choice,The optimal consumption bundle is the consumption bundle that maximizes a consumers total utility given his or her budget constraint.,Sammys Budget and Total Utility,Sammys total utility is the sum of the utility he gets from clams and the utility he gets from potatoes.,Q

11、uantity of potatoes (pounds),5,4,3,2,1,0,10,8,6,4,2,A,A,B,B,C,C,D,D,E,E,BL,Utility function,F,F,5,4,3,2,1,0,80,70,60,50,40,30,20,10,Quantity of clams (pounds),0,2,4,6,8,10,(a),Sammys Budget Line,(b),Sammys Utility Function,The optimal consumption bundle,Quantity of clams (pounds),Quantity of potatoe

12、s (pounds), maximizes total utility given the budget constraint,Total utility (utils),Optimal Consumption Bundle,Sammys total utility is maximized at bundle C, where he consumes 2 pounds of clams and 6 pounds of potatoes. This is Sammys optimal consumption bundle.,Spending the Marginal Dollar,The ma

13、rginal utility per dollar spent on a good or service is the additional utility from spending one more dollar on that good or service.,Sammys Marginal Utility per Dollar,Marginal Utility per Dollar,If Sammy has, in fact, chosen his optimal consumption bundle, his marginal utility per dollar spent on

14、clams and potatoes must be equal.,6,5,4,3,2,1,MU,P,/,P,P,C,5,4,3,2,1,0,0,2,4,6,8,10,Total utility (utils),Quantity of clams (pounds),Quantity of potatoes (pounds),At the optimal consumption bundle, the marginal utility per dollar spent on clams is equal to the marginal utility per dollar spent on po

15、tatoes.,Optimal Consumption Rule,The optimal consumption rule says that when a consumer maximizes utility, the marginal utility per dollar spent must be the same for all goods and services in the consumption bundle.,From Utility to the Demand Curve,The main reason for studying consumer behavior is t

16、o understand how the downward slope of the market demand curve is explained by the utility-maximizing behavior of individual consumers.,Marginal Utility, the Substitution Effect, and the Law of Demand,The substitution effect of a change in the price of a good is the change in the quantity consumed o

17、f that good as the consumer substitutes the good that has become relatively cheaper for the good that has become relatively more expensive.,The Income Effect,The income effect of a change in the price of a good is the change in the quantity consumed of that good that results from a change in the con

18、sumers purchasing power due to the change in the price of the good. Normal Goods Inferior Goods Giffen Goods,Consumers maximize a measure of satisfaction called utility. Each consumer has a utility function that determines the level of total utility generated by his or her consumption bundle, the go

19、ods and services that are consumed. A goods or services marginal utility is the additional utility generated by consuming one more unit of the good or service. We usually assume that the principle of diminishing marginal utility holds: consumption of another unit of a good or service yields less additional utility than the previous unit.,A budget constraint limits a consumers spending to no more than his or her income. It defines the consumers consumption possibilities, the set of all af