Within this section we will focus on determining the difference
between marginal benefit and marginal cost, as well as how to
calculate the efficient quantity.
Consumer Choice
Economic analysis generally
assigns the following properties to consumers:
- Consumers make rational decisions. If two
products are of equal benefit to a consumer, then he or she will
choose the cheaper product. If two products are the same price, the
consumer will choose the one that provides the higher benefit.
- Limited income enforces choice. Consumers
have to make choices as to what goods will be purchased or not
purchased. Purchasing one item means that less funds are available
to purchase other items.
- Substitution of goods. Consumers can
achieve satisfaction, which is generally referred to asutility, with many
choices. The satisfaction and cost of a cheeseburger can be
evaluated in comparison to other goods - such as hot dogs.
- The Law of
Diminishing Marginal Utility. This law refers to marginal
utility, which describes the increase in satisfaction from
consuming one additional unit of the good. The Law of Diminishing
Marginal Utility states that as each additional unit of a good is
consumed, the amount of marginal (incremental) utility will
decrease.
Economists believe that consumers make decisions at the margin;
i.e. should one more unit of the good be obtained or not? The
consumer will compare the additional (marginal) utility to be
achieved by consuming one more unit of the good, to the additional
(marginal) utility that must be given up (buying power) in order to
obtain the good. At any particular price, the consumer will
continue to buy units of the good as long as the marginal benefit,
as expressed by maximum willingness to pay, exceeds the price. The
marginal benefit indicates, in dollar terms, what the consumer is
willing to pay to acquire one more unit of the good; it can also be
related to the height of an individual's demand curve. Another
implication of the Law of Diminishing Marginal Utility is that the
height of the demand curve will fall as more units of the good are
consumed.
Another implication of marginal utility theory is that for
consumers to maximize utility, the following relationship
holds:
MUa =
MUb =
MUc =
and so on...
P
a P
b P
c
MU refers to marginal utility of the good, P represents the price
of the good, and the subscripts indicate a particular good. The
last unit of each good purchased will provide the same marginal
utility per dollar spent on that good.
The term marginal cost refers to the
opportunity cost
associated with producing one more additional unit of a good.
Opportunity cost is a critical concept to economics - it refers to
the value of the highest value alternative opportunity. For
example, in examining the marginal cost of producing one more
bushel of wheat, that number could be expressed as the dollar value
of corn or other goods that could be produced in lieu of more
wheat.
Marginal benefit refers to what people are willing to give up in
order to obtain one more unit of a good, while marginal cost refers
to the value of what is given up in order to produce that
additional unit. Additional units of a good should be produced as
long as marginal benefit exceeds marginal cost. It would be
inefficient to produce goods when the marginal benefit is less than
the marginal cost. Therefore an efficient level of product is
achieved when marginal benefit is equal to marginal cost.
Consumer Surplus and Marginal
Benefit
Consumer surplus represents the difference
between what a consumer is willing to pay and the actual price
paid. If a consumer is willing to pay $5.00 for a gallon of
gasoline, and the actual price is $3.00, then there is a consumer
surplus of $2.00 with the purchase of that gallon of gasoline. The
value to the consumer, or marginal benefit, is $5.00. Value is
calculated by getting the maximum price that consumers are willing
to pay.
We expect consumers to continue purchasing units of a good as long
as the marginal benefit exceeds the price paid; i.e., as long as
there is a consumer surplus to be achieved.