Screening And Signaling
When a person buys a used car from a stranger, the buyer knows
that the purchase involves risks. The seller may tell him that the car
has always worked well, but the buyer cannot be sure that the seller is
truthful. It is in the interests of the seller to say these things,
whether or not they are true. The seller of a "lemon" could say the
same thing as the seller of a quality item. Economists say that markets
in which one side of the transaction has better knowledge than the
other, as in this case, have asymmetric information. In this example sellers of quality
items need a way of communicating information to buyers so
that only truthful information will be transmitted.
How do sellers convince buyers of the attractive
qualities of their products? Or how do buyers seek to filter
out erroneous information? Sellers of high-quality items
must find a way to signal information about their
products, and these signals must be difficult for those
selling low-quality products to duplicate. Buyers must
screen out erroneous information, but allow in
truthful information. These problems do not exist in markets
in which products are simple and easily evaluated. There is
little need for this behavior in many agricultural markets,
for instance.
One way a seller can signal the quality of its product is
by offering guarantees or warranties. If a firm offers a warranty
on a poor product, it will suffer a loss. Therefore, it is
in the firm's interests to only offer a warranty on a
quality product. The warranty tells potential buyers that
the firm will stake money on its belief that it has a
good-quality product.
Another way a firm can signal quality is by building a
brand name. A brand name is valuable only if
consumers associate it with quality, and the firm can build
this association only with time and resources. Once a brand
name is established, it is in the interests of the firm to
protect it by not offering a poor-quality product with its
brand name. When a firm with an established brand name does
offer a poor-quality product, it usually puts a different
name on the product so as not to endanger the public's
perception of its brand name.
Signaling plays an important role in the labor market. An
employer has little information about a prospective
employee, and cannot expect truthful answers if he asks
whether the applicant is intelligent, has leadership
qualities, and is responsible. Instead, the applicant must
try to prove that he has these qualities. A college
education is a way of signaling intelligence and
perseverance. Leadership can be signaled by extracurricular
activities. In fact, some students seek leadership positions
primarily for their value as ways to signal leadership to
future employers. The purpose of a resume is to list those
activities that will signal attractive qualities to
potential employers.
The fact that a college education can signal qualities to
employers has raised some interesting questions about why
people get college educations. A popular answer among
economists has been that education builds human
capital, that is, it is a way of investing in people to
increase their productivity. More recently some economists
have suggested that this view is wrong or at best only
partly true, and that college education mostly serves as a
way of signaling to future employers. If education is merely
a way of signaling, if it is only a complex gauntlet that
eliminates those who are not intelligent and do not have
perseverance, then the social usefulness of college
education may not be very great. From the viewpoint of the
student, it does not matter--the benefits are the same
either way. Though most economists believe that education
both builds human capital and acts as a signal, the relative
importance of these two functions is still disputed.
Signaling is an action by a party with good information that is confined to situations of asymmetric information. Screening, which is an attempt to filter helpful from useless information, is an action by those with poor information and it occurs even when information is symmetric. When two people go on a blind date, both are unsure if they are compatible, so both are screening, listening and watching to learn if the other person is someone with whom they would want a second date. (It is possible that both may be signaling as well, because each has information that the other does not have.)
There are many examples of screening in employment decisions. Employers give aptitude tests and check letters of recommendation. The existence of
"old-boy" networks is the result of a screening process. If
a person wants to hire someone, he will ask those he trusts
(the "old boys") for recommendations. Because recommending
someone who is unqualified will lower his prestige in the
eyes of the other "old boys," there is an incentive for a
person to only recommend qualified applicants.1
Also, part of the enthusiasm that employers have for
graduates of prestigious MBA programs is that the schools
are selective about who they let in. They try to select only
those students who have the right combinations of
intelligence and personality traits to ensure success in the
business world. Thus, prestigious MBA programs act as a
screening agency for business. This, as much as what they
teach their students, may account for the high salaries
their graduates command.
When there is asymmetric information in the market, screening can involve incentives that encourage the better informed to self-select or self-reveal. For example, a job with a low-paying probationary period will discourage those who know they are not well-suited for the position from applying. People who are confident that they will survive the probationary period are more likely to find the offer attractive than those who doubt their ability. A lender who demands collateral for a loan discourages applications from those who doubt their ability to repay. (Collateralized loans do more than screen, but screening is one of their functions.) People who expect to use insurance find deductibles more of a burden than those who do not expect to make claims. Hence, insurance companies use deductibles to sort policyholders into different risk classes and charge accordingly.
In the discussion of efficiency we considered the case in
which a bundle of resources had three possible uses: one
valued at $25, one at $22, and one at $20. We concluded that
an efficient market sent those resources to the place where
they were worth $25. Suppose, though, that this use has an
information problem, so the seller must spend $5 to signal
to the buyers that the product really is worth $25. Will the
resources go to the most valuable use?
Next we begin a discussion of risk
and uncertainty.
1Of course, this "old boy"
system makes it very difficult for qualified applicants
outside the system to get in. The existence of the problems
that make signaling and screening necessary tends to protect
those who are already established.
Copyright
Robert Schenk
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