Key Concepts and Summary

Key Terms

behavioral economics a branch of economics that seeks to enrich the understanding of decision-making by integrating the insights of psychology and by investigating how given dollar amounts can mean different things to individuals depending on the situation budget constraint (or budget line) shows the possible combinations of two goods that are affordable given a consumer’s limited income consumer equilibrium point on the budget line where the consumer gets the most satisfaction; this occurs when the ratio of the prices of goods is equal to the ratio of the marginal utilities. diminishing marginal utility the common pattern that each marginal unit of a good consumed provides less of an addition to utility than the previous unit fungible the idea that units of a good, such as dollars, ounces of gold, or barrels of oil are capable of mutual substitution with each other and carry equal value to the individual income effect a higher price means that, in effect, the buying power of income has been reduced, even though actual income has not changed; always happens simultaneously with a substitution effect marginal utility the additional utility provided by one additional unit of consumption marginal utility per dollar the additional satisfaction gained from purchasing a good given the price of the product; MU/Price substitution effect when a price changes, consumers have an incentive to consume less of the good with a relatively higher price and more of the good with a relatively lower price; always happens simultaneously with an income effect total utility satisfaction derived from consumer choices

Key Concepts and Summary

6.1 Consumption Choices

Economic analysis of household behavior is based on the assumption that people seek the highest level of utility or satisfaction. Individuals are the only judge of their own utility. In general, greater consumption of a good brings higher total utility. However, the additional utility people receive from each unit of greater consumption tends to decline in a pattern of diminishing marginal utility. We can find the utility-maximizing choice on a consumption budget constraint in several ways. You can add up total utility of each choice on the budget line and choose the highest total. You can select a starting point at random and compare the marginal utility gains and losses of moving to neighboring points—and thus eventually seek out the preferred choice. Alternatively, you can compare the ratio of the marginal utility to price of good 1 with the marginal utility to price of good 2 and apply the rule that at the optimal choice, the two ratios should be equal:

6.2 How Changes in Income and Prices Affect Consumption Choices

The budget constraint framework suggest that when income or price changes, a range of responses are possible. When income rises, households will demand a higher quantity of normal goods, but a lower quantity of inferior goods. When the price of a good rises, households will typically demand less of that good—but whether they will demand a much lower quantity or only a slightly lower quantity will depend on personal preferences. Also, a higher price for one good can lead to more or less demand of the other good.

6.3 Behavioral Economics: An Alternative Framework for Consumer Choice

People regularly make decisions that seem less than rational, decisions that contradict traditional consumer theory. This is because traditional theory ignores people’s state of mind or feelings, which can influence behavior. For example, people tend to value a dollar lost more than a dollar gained, even though the amounts are the same. Similarly, many people over withhold on their taxes, essentially giving the government a free loan until they file their tax returns, so that they are more likely to get money back than have to pay money on their taxes.

Self-Check Questions

1 . Jeremy is deeply in love with Jasmine. Jasmine lives where cell phone coverage is poor, so he can either call her on the land-line phone for five cents per minute or he can drive to see her, at a round-trip cost of $2 in gasoline money. He has a total of $10 per week to spend on staying in touch. To make his preferred choice, Jeremy uses a handy utilimometer that measures his total utility from personal visits and from phone minutes. Using the values in Table 6.6, figure out the points on Jeremy’s consumption choice budget constraint (it may be helpful to do a sketch) and identify his utility-maximizing point. Round Trips Total Utility Phone Minutes Total Utility 0 0 0 0 1 80 20 200 2 150 40 380 3 210 60 540 4 260 80 680 5 300 100 800 6 330 120 900 7 200 140 980 8 180 160 1040 9 160 180 1080 10 140 200 1100 TABLE 6.6 2 . Take Jeremy’s total utility information in Exercise 6.1, and use the marginal utility approach to confirm the choice of phone minutes and round trips that maximize Jeremy’s utility. 3 . Explain all the reasons why a decrease in a product's price would lead to an increase in purchases. 4 . As a college student you work at a part-time job, but your parents also send you a monthly “allowance.” Suppose one month your parents forgot to send the check. Show graphically how your budget constraint is affected. Assuming you only buy normal goods, what would happen to your purchases of goods?

Review Questions

5 . Who determines how much utility an individual will receive from consuming a good? 6 . Would you expect total utility to rise or fall with additional consumption of a good? Why? 7 . Would you expect marginal utility to rise or fall with additional consumption of a good? Why? 8 . Is it possible for total utility to increase while marginal utility diminishes? Explain.