Utility analysis is primarily taught in introductory courses. A more sophisticated version of consumer demand theory relies on the analysis of indifference curves and is more commonly found at the intermediate course level and above.

Utility and Satisfaction

When used in the analysis of consumer behavior, utility assumes a very precise meaning, which differs from the everyday use of the term. In common use, the term utility means "useful." For example, a "utility" knife is one with many uses, something that is handy to have around. In baseball, a "utility" player can perform quite well at several different positions and is thus useful to have on the team. Moreover, a public "utility" is a company that supplies a useful product, such as electricity, natural gas, or trash collection.

In contrast, the specific economic use of the term utility in the study of consumer behavior means the satisfaction of wants and needs obtained from the consumption of a commodity. The good consumed need not be "useful" in the everyday sense of the term. It only needs to provide satisfaction.

In other words, a frivolous good that has little or no practical use, can provide as much utility as a more useful good.

• An OmniOpen Deluxe Can Opener is extremely useful, especially when a sealed can needs to be opened.


• An autographed photo of Brace Brickhead, Medical Detective, is not very useful. It does nothing but rest peacefully in a picture frame.

The Law of Demand

The explanation of the law of demand using utility analysis is relatively simple. Consumers purchase goods that satisfy wants and needs, that is, generate utility. Those goods that generate more utility are more valuable to consumers and thus buyers are willing to pay a higher price. The key to the law of demand is that the utility generated declines as the quantity consumed increases. As such, the demand price that buyers are willing to pay decreases as the quantity demanded increases.

Total Utility

Total Utility

Utility analysis is based on the presumption that the amount of utility generated from the consumption of a good can be explicitly measured. The standard hypothetical measurement unit is "utils."

Suppose, for example, that Edgar Millbottom spends a day riding the Monster Loop Death Plunge roller coaster at the Shady Valley Amusement Park, then records the amount of total utility achieved at the end of each ride. The two columns presented in the table measure the number of rides and the total utility accumulated by Edgar at the end of each ride (in utils).

• Before his first ride, Edgar receives no utility. No activity, no utility.


• Edgar's first ride generates 11 utils of utility.


• The total utility generated if Edgar takes 8 rides is 32 utils.


• Edgar's utility increases for the first 6 rides, reaching a high of 36 utils, before declining back to 32 utils for the 8th ride.


• Presumably Edgar's utility continues to decline after the 8th ride.


• Edgar obtains the highest total utility from 6 rides on the roller coaster.

In many situations, however, the consumption of a good faces constraints. Edgar, for example, might face a time constraint because he plans to attend a live concert of the rock-and-roll group, Live Headless Squirrels, that prevents him from riding more than 4 times. Or he might face an income constraint because the amusement park charges $1 per ride and he has only $5 in his pocket.

In these situations Edgar, as well as other consumers, might pursue constrained utility maximization. This means achieving the highest possible utility, given certain restrictions that prevent the highest overall level of utility from being achieved.

Marginal Utility

Marginal utility is specified as:

marginal utility

=

change in total utility change in quantity

If, for example, total utility increases from 20 to 27 utils, then marginal utility is 7 utils.

Marginal Utility

The far right column of this table presents marginal utility values derived from each ride Edgar undertakes. Marginal utility from the first ride is 11 utils. The extra utility generated by the second ride is 9 utils. The third ride provides another 7 utils. The remaining numbers in the right column are interpreted in a similar manner.

Marginal utility provides a direct link between utility analysis and demand. The demand price a buyer is willing to pay for a given good is based on the marginal utility derived from consuming the good. In this example, Edgar is most likely willing is to pay more for the first ride than the fifth ride, in that the first ride generates 11 utils of satisfaction, but the fifth ride generates only 3 utils.

The Law of Diminishing Marginal Utility