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Working Paper 8902

A TWO-SECTOR IMPLICIT CONTRACTING MODEL
WITH PROCYCLICAL QUITS AND INVOLUNTARY LAYOFFS
by Charles T. Carlstrom

Charles T. Carlstrom is an economist
at the Federal Reserve Bank of Cleveland.
Working papers of the Federal Reserve Bank of
Cleveland are preliminary materials
circulated to stimulate discussion and
critical comment. The views stated herein
are those of the author and not necessarily
those of the Federal Reserve Bank of
Cleveland or of the Board of Governors of the
Federal Reserve System.

February 1989

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A Two-Sector Implicit Contracting Model
With Procyclical Quits and Involuntary Layoffs

I. Introduction
Empirical studies of mobility in the labor market have shown that quits
are procyclical and layoffs are countercyclical. In addition, most economists
believe that at least some layoffs are involuntary. That is, laid-off workers
are worse off than they would be if they could have continued working at the
wage paid to retained workers. The purpose of this paper is to develop an
implicit contracting model to help explain these phenomena.
Equilibrium models of unemployment have failed to explain why some
unemployment might be involuntary. For example, Lucas and Prescott (1974)
imply that workers will become unemployed if their expected present discounted
value of future utility is greater than or equal to their discounted value of
future utility when they are unemployed. Another objection to using search
models to explain unemployment is the assumption that unemployed search is
more productive than employed search. This assumption has frequently been
questioned.
Implicit contracts provided one of the first attempts to explain
involuntary unemployment as an equilibrium phenomenon. In Azariadis' (1975)
seminal work, involuntary unemployment results because firms cannot make
severance paymentsto laid-off workers. In particular, Azariadis assumes that
1) workers are risk averse while firms are risk neutral, 2) working is a 0 or

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1 decision, that is, hours worked per worker is not a choice variable, and 3)
firms cannot make severance payments to unemployed workers. The optimal
contract calls for workers to become unemployed during certain states of
nature and, because of the no-severance-payment assumption, to consume the
value of their leisure. Because workers are risk averse, they desire a
constant consumption stream, and hence it is not optimal to lower the
consumption of employed workers in bad states in order to induce them to
leave.
Another characteristic of Azariadis' model is that whenever there is
involuntary unemployment there is also overemployment, that is, overemployment
occurs because there is more employment (and less unemployment) than would
occur in a pure Walrasian market. Workers remain employed even though their
marginal productivity of labor is less than their reservation wage. Both
involuntary unemployment and overemployment result from the assumption that
firms cannot make severance payments to laid-off workers. As a result,
the implication is that firms will partially insure workers against the risk
of being laid off by having more employment than would occur in a pure
Walrasian market. Once severance payments are allowed, unemployment becomes
purely voluntary and production is efficient.
The goal of this paper is to integrate a simple model of on- the-job search
with an implicit contracting model. One objective is to be able to explain
involuntary unemployment without placing any a priori restrictions on
severance payments. Like Azariadis' model, the model predicts that there will
be overemployment whenever there is involuntary unemployment. This is in
contrast to Grossman and Hart (1983), who developed a model to explain

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underemployment. A recent paper by Oswald (1986) provides one of the first
attempts to explain both involuntary unemployment and underemployment, but to
do so he exogenously assumes that severance payments are zero.
In order to explain involuntary unemployment, it is promising to follow
the lines of Kahn (1985).

He showed that complete insurance is not possible

(or that wages will not be independent of the state of nature) when a firm
cannot monitor a worker's alternative wage offer. Arvan (1986) extended
Kahn's analysis and suggested that this might explain why involuntary layoffs
occur. In Arvan's model, firms cannot insure against layoffs because of the
need to promote on-the-job search. However, Arvan implicitly constrains the
severance payment to laid-off workers to equal the severance payment offered
to those who voluntarily quit their jobs. It is this assumption that enables
him to explain involuntary unemployment.
This paper is similar to those by both Kahn and Arvan. It also extends
the implicit contracting framework by developing a model that can explain why
quits are procyclical. The structure of the paper is as follows. Sections
11-IV consider a one-sector version of the model, where only the primary
sector is explicitly modeled. Section I1 considers the case where a firm can
observe both a worker's search intensity and whether the worker receives a job
offer. I show that the optimal contract for this case implies complete
insurance.
Section I11 drops the assumption that a firm can observe a worker's
search intensity, but assumes that the firm can observe which workers receive
job offers and can hence make severance payments conditional on the worker's
accepting an offer. This section shows that the firm's inability to observe a
worker's search efforts is not sufficient to produce involuntary unemployment.
However, the optimal contract does result in incomplete risk-sharing because

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firms trade off their desires to provide incentives for on-the-job search and
to insure workers against future wage changes. The optimal contract is also
characterized by production efficiency for laid-off workers. However, workers
who receive job offers are shown to leave more often than they would in a
Walrasian world.
Section IV shows that when firms cannot observe both a worker's search
efforts and whether the worker receives a job offer, the incentive-compatible
contract implies that laid-off workers will be worse off than their employed
counterparts. Involuntary unemployment provides the proper incentive in bad
states of nature for job-finders to reveal that they received an offer.
Section V extends the previous analysis by explicitly modeling both sectors.
I show that a two-sector implicit contracting model can help explain why quits
are procyclical. The model also predicts that while fewer workers receive job
offers in such a model, there are states of nature that promote more mobility
than in a Walrasian labor market. For example, in some states of nature, both
sectors will be hiring workers from the other sector. This occurs because
firms must provide incentives for on-the-job search.

11. The Model with Symmetric Information
Consider an economy that lasts for two periods indexed by t

=

1, 2. Labor

is hired in the first period, and production takes place according to a
deterministic production function f(N).

Production in the second period is

subject to a random shock, 6, where the range of 6 is the closed interval

[O, Ow],with a density function and a cumulative distribution function of
g(0) and G(0), respectively. During the first period, workers can search
for alternate work in another sector in case of a bad shock to the industry's
output in the second period.

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In the first period, workers choose their search effort. The probability
of finding a job is assumed to be an increasing function of effort expended on
search, but the workers' utility is assumed to be a decreasing function of
effort expended on search. These relationships are expressed by a function
c(X), which indicates the disutility associated with expending enough search
to find a job with probability A.
The cost of pursuing on-the-job search is assumed not to affect a worker's
marginal utility of income. In that sense, searching can be thought of as
requiring a "psychic" cost c(A).

Preferences are given by U(C

+

BL) - c(X),

where L is leisure, B is the value of leisure or the reservation wage of a
worker, and C is consumption. The following restrictions are placed on
utility: L

E

[O, 11, 0 2 X 5 1, U1'(.) < 0, and c"(X)

> 0.

Restricting L to be either one (not working) or zero (working) assumes that
hours worked is not a choice variable. Searching also is assumed not to
affect the productivity of a worker. The assumption that search effort enters
separably in the worker's utility function is not crucial; it is meant to aid
comparison with other implicit contracting models.
An alternative explanation of the model is that workers must undergo
training on the job if they wish to switch to another sector. The cost of
training would be c(X), where X is the probability that the training is
successful. The same restrictions as before would be placed on c(X).
A worker's productivity (and hence wage) at the alternate sector is
exogenously given to be w'.

Searching does not affect this productivity/wage

offer. That is, plants are either productive and produce w', or are not
productive. It is also assumed that the firm cannot hire workers in the
second period. This assumption will be dropped later so that additional labor
can be hired in period two at the market wage rate, w'.

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A quit is defined to be a job change, while a layoff is defined to be a
transition from employment to unemployment. These definitions are motivated
by the empirical regularity that most people who report being laid off become
unemployed (at least temporarily), while workers who report quitting their
previous job typically do not have an intewening spell of unemployment.
Contracts consist of wages, severance payments, layoff probabilities, and
a search intensity. That is, a contract consists of (wl,w2(0),

1(0),

q(0),

sl(0) , sq(0), A ) , where wl is the first-period wage; w2(B)
is the second-period wage chosen in period one contingent upon the realization
of 0 in period two; and l(0) is the fraction of workers without outside
offers who are laid off, while q(0) is the fraction of workers who receive
outside offers who quit; and sl(0) and ~ ~ ( 0are
) the severance
payments (or taxes) given to (or applied to) workers who did not receive job
offers and workers who did receive job offers, respectively. For the
full-information case considered below, one can think of the firm as also
choosing the search intensity of workers, A .
Defining V(.) to be the discounted value of utility for a representative
worker and assuming that workers cannot save or dissave so that their
consumption in every period is equal to their wage in that period, the
expected utility of a representative worker equals

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The intuition is as follows: X(1-q(8))

is the probability that a worker

receives a job offer from outside, but remains employed at his original firm
is the probability that a worker receives a job
;
earning ~ ~ ( 8 )Xq(8)
offer and accepts it, in which case he earns w' plus a severance payment
sq(8); (1-X)(l-l(8))

is the probability that a worker does not find a

job and is not laid off, in which case he earns ~ ~ ( 8 ) (1-X)1(8)
;
is
the probability that the worker does not receive a job offer and is laid off,
in which case he earns the value of his leisure, B, and a severance payment,
sl(8).

The firm is assumed to maximize profits where profits are

given by

The optimal employment contract maximizes expected utility subject to
nonnegative profits.

The first-order conditions can be characterized by the following equations:

(1)

U' (w,)

=

U' (~~(8)) = U' (w1+sq(6'))

=

U' (B+sl(8))

=

Y,,

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(2)

Bf'([l-Xq(B)]N)

(3)

Bfl([(l-1(8))(1-X)]N)
q(B)=l,

1(B)

=

=

c' (A)

where

-y

=

w' when O > BE,

=

B when B < OL

0 when OL < O < OH

where B,f' ([I-X]N)

(4)

8

=

B, 6,f' ([I-X]N)

=

w' ,

7,[G(OL) (w' -B) + eL~eE(~' - Of' ((1-X)N)g(B)dB] ,

is the Lagrangian multiplier associated with the expected profit

constraint and -yl

=

N-y.

The solution to this problem is straightforward. Since there are no
informational asymmetries, the optimal contract involves both perfect
risk-sharing and production efficiency. From (I), workers are guaranteed the
same income (or income equivalent) during all states of the world, independent
of both the state of nature and whether a worker receives a job offer.
Workers who are successful in their job search subsidize those who are
unsuccessful. From (2) and (3) we have production efficiency. Workers are
laid off only after all workers who received outside offers have quit. Since
w' > B, it is cheaper for the firm to let all the workers with outside offers
quit and earn w' than to lay off a worker who has an income equivalent of B.
When B > OH, no workers are laid off and workers with outside offers quit
until the marginal productivity of the remaining workers equals the wage
earned by the workers who quit, w'.

After workers with outside offers leave,

firms do not start laying off workers until the marginal productivity of labor
equals the reservation wage for a worker without an outside offer, B, < B

< B,.

When B < B,, firms lay off workers until the marginal

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productivity of labor is equal to the reservation wage of the marginal worker.
Firms then subsidize workers who are laid off by giving them a severance
payment so that they are indifferent between staying with the firm or leaving.
Firms also force workers to supply the optimum amount of search intensity
given by (3).

One can think of wages being set equal to zero when workers

supply less than the required amount of search effort. The marginal cost of
searching is equal to the marginal benefit of searching. The marginal benefit
of searching is the difference between what the worker would earn in an
alternate job, w', and what he produces in his current job, Of'(.).
states of nature (B > B,)

In good

this difference is zero from production

efficiency, while in bad states of nature (B < BL) the difference is w'-B.
When BL < B < 0, (that is, q(B)

w'

-

Of'(.)

=

1,1(8)

=

0), this difference is

otherwise. The marginal benefit of searching is therefore the

difference between what the worker would earn if he quit and what he would
produce if he stayed. Since the marginal cost of searching has units of
utilities, this quantity is multiplied by a worker's marginal utility of
income.
This contract specifies that all workers receive the same utility whether
or not they succeed in finding outside alternatives. Hence, if firms did not
know how hard a worker had searched, this contract would offer no incentive
for workers to search. The next section considers the optimal contract when a
firm cannot monitor a worker's search intensity.

111. Imperfect Monitoring
In this section, it is assumed that a worker's search intensity is known
only by the worker. However, it is assumed that the following contingency can

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be included in the optimal contract: severance payments can be made
conditional on the worker's accepting a job offer. With asymmetric
information, firms choose the optimal contract on the assumption that workers
will then choose A to maximize their utility given this contract. That is,
given a contract (wl,w2(e>, sq(B>, sl(B),

q(d),

1(0)1,

workers will choose their desired search intensity, A*, such that

To solve for the optimal contract, we replace the above condition with the
first-order condition for an agent's search effort. It shows how agents
choose X in response to the employment contract. This incentivecompatibility constraint is appended to the optimal contract problem in the
previous section giving

S( (1-q(e))u(w2(e))
-

J'(

(1-1(6'))U(w2(e)

+ q(e)u(wf+sq(e>)

)g(e)de

+ l(O)U(B+~~(O)))g(e)de

-

C'(A)

=

0.

The first-order conditions can be characterized by the following
equations:

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(2) u' (w2(B))

(5)

q(8)

=

=

r,[A(e> (l-q(e>>+(l-x>(1-1 (s>>I
[(A*,)
(1-q(B))+(l-A-7,) (1-1 (B))]

W(B)

1

if

q*~)

where W(6)

0

if

- efl((l-~)[l-1(8)]~) >

0

- Bfl([A(l-q*(B)+(l-A)(l-1)]N)
W(B) - Bfl([l-(1-A)I]N) < 0

=

0

where
W(0)

=

w'

+

(U(wl+sq) - U(w2)

1
(6)

l(8)

=

if

1*(B)

-

U' (wl+sq)
[(w'+sq)

- w,] I/U1(wl+sq)

B - Bf'(A(1-q(B))

>0

- Bfl([A(l-q(B)+(l-A)[l-l*(B)]N)
B - Bfl((l-Xq(B))N) < 0

where B
if

0

From equations ( 5 ) , ( 6 ) , and (7) we obtain:

q(8)

=

1, l(8) > O when B < BL

q(8)

=

1, l(8)

=

0 when B L <

q(8) < 1, l(8)

=

0 when B > BE

B < OH

7,(l-A)
(2a) U1(w2(e>> = (1-A-7,) when 0 < BL

(2b) u' (w~O))

=

7,(l-xq(e)>
[1-(1\+72)q(fi)] when B > BL

where BLfl([I-A]N) = B, OHfl([I-A]N) = W(B).

=

0

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Like the case with symmetric information,(5a) and (5b) show that layoffs
occur only after all workers with outside offers accept employment. From (2a)
and ( 4 ) , when 6' < BL, layoffs occur and there is complete insurance for
laid-off workers, that is, B

+

sl

=

w2. When 6' > OH, not all

workers with outside offers accept new jobs. From (2b) and ( 3 ) , workers who
receive job offers and leave the firm are subsidized and earn more than those
who do not find other employment, that is, w'

+

sq > w2. However, this

differential gets smaller with better states of nature.
Since workers are risk averse, the definition of W(6') in equation(5) and
(2b) implies that when OL < 6' < OH, the marginal productivity of labor
will decrease with better states of nature. Similarly, using the fact that
U ( C ) is concave, the definition of W(6') and (5) shows that workers with

outside offers are allowed to leave the firm more often than they did with
symmetric information, that is, W(6') > w'.

The intuition behind this result

is that on-the-margin firms find it optimal to provide additional incentives
for on-the-job search by allowing workers to earn more after they find another
job, and also by allowing them to leave more often than they would if they had
full information. From (5), the amount that production differs from a
Walrasian market depends on the curvature of the utility function. The more
risk-averse the worker, the greater the need to insure his income. Since
insurance results in less search effort, firms provide incentives for
on-the-job search by allowing workers to leave more often than in a world with
symmetric information.
It should be noted that the above solution assumes that firms have the
power to either subsidize or tax workers who leave. When 6' > OH, the firm
announces that the first q(6')N workers who volunteer to leave can do so with
a severance payment of ~~(6').The rest of the job-finders voluntarily stay

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at the firm if w' < w2. However, if w' > w2, the firm must tax the
successful workers to prevent them from leaving.
Since workers respond optimally to changes in the contract offered to
them, equation (7) states that their search intensity will be chosen so that
the change in the marginal cost to workers from increasing their search effort
is equal to the marginal benefit (expressed in units of utility) to the firm
resulting from workers' increasing their search effort. The marginal benefit
from increasing a worker's search intensity is the difference between what the
worker is paid, w2, and the sum of what he produces, Of1(.), and the
severance payment given to departing workers, sq(0).

The proof that y2

is strictly positive follows because when -y2 < 0 , workers would have no
incentive to search. A sufficient condition for an interior solution to occur
is that c'(0)

=

0, cl(l)

= a

and w' > B, that is, it is costless to exert a

little search effort, but the marginal cost of searching so that a worker can
ensure a job offer is infinitely costly.
Note that when Ofl(X(l-q*(O)N)

> w', there is an incentive for workers

who receive job offers to recontract with the firm. This is not possible,
however, given the assumption that firms can observe which workers received
job offers after the offers were accepted. In addition, there is an implicit
assumption that firms cannot hire these workers back after the offer has been
accepted. If the firm could costlessly observe a worker's offer, there would
always be production efficiency because firms could bribe workers who found
jobs to continue employment by offering them a higher wage rate, w'.
If the marginal productivity of labor is greater than w', then the firm has an
incentive to induce workers who received an offer to stay, since they can
produce more at their present job than they can at an alternative job.

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Underemployment results when OL < 9 < BH because firms, by
assumption, cannot hire workers in the second period at the market wage rate,
w'. If additional labor can be hired, then an interesting result occurs.
Workers will leave the firm while other workers are being hired by the firm.
Since the marginal productivity of labor is greater than w', the firm has an
incentive to hire additional workers at a wage of w f.

Although ex post this

seems wasteful (because of possible moving costs that are not built into the
model), ex ante such behavior is necessary in order to motivate workers to
engage in on- the -job search.
To formalize, assume that the firm can hire n(9) workers in the second
period at a market wage rate of w f . The optimal contract is then to
choose (wl(9), w2(S),

sq(S), sl(9), q(9), 1(9),

A, n(9))

in order to maximize

expected utility subject to the constraint of nonnegative profits, the
incentive-compatibility constraint, and the restriction that additional
employment in period two be nonnegative:

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The first-order conditions can be characterized by the following
equations:

1
q(B)

(5)

=

q*(B)

0

if

W(B)

-

Bf'((1-A) [1-l(9) ]N+n(B))

where

W(B)

-

Bfl([X(l-q*(B)+(l-A)(l-l)]N+n(B))

if

W(0)

-

Bfl([l-(1-X)l]N+n(e))

<

>0
=

0

0

where
W(B)

=

w'

+

1

(6)

(7)

l(9)

n(B)

=

=

-

(U(wl+sq) - U(w2)
if

U' (wl+sq)[(wl+sq) - w2]) / U 1(wl+sq)

B - Bfl(X(l-q(B)+n(B))

l*(B) where

B - Bfl([X(l-q(B)+(l-X)(l-l*(B))]N+n(B))

0

if

B

w

if

w'

where

w' - Bfl(X(l-q(B)+(l-X)(l-l(B))]N+n*(B))

if

w'

n*(B)

0

-

Bfl((l-Aq(B))N+n(B))

-

=

1, l(8) < 0, n(B)

<

0

=

0

0

- Ofl(x(l-q(e)+(l-~)(l-I(B))]N)<

=

=

eft(-) > 0

Using e.l), e.2), e.3), and b) yields:
q(B)

>0

0 when 0 < BL

0

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0 when BL < B < OH

q(0)

=

1, 1(B)

=

0, n(B)

q(B)

=

1, l(19)

=

0, n(B) > 0 when 6' > BH

=

where BLff([1-X]N) = B, BHfl([1-X]N)

=

w' .

The results when the firm can hire additional workers at a wage of w' are
as follows. Workers who stay with the firm earn a wage w2, which is
independent of the state of the world. Workers who receive job offers accept
their offers and receive a severance payment from the firm, sg, which is
also state-independent. When firms lay off workers, that is, when B < BL,
there are complete severance payments and production efficiency. All workers
with outside offers will quit and no additional workers will be hired in these
states of nature. When BL < B < OH, all workers with outside offers
quit, no workers are laid off, and no additional workers are hired. When
0 > OH, all workers with outside offers quit and no workers are laid off,
but the firm hires additional workers at a wage of w' until production
efficiency prevails.
The contract implies a two-tier system for adjusting a firm's work force.
Firms first offer a severance payment to workers who wish to leave the firm.
Every worker who has found another job will then accept this offer. In more
complex models, one can think of the severance payment offered to departing
workers as also consisting of possible early retirementbenefits, etc. After
workers accept this offer, the firm then adjusts the labor force by laying off
workers or hiring workers until it reaches the desired level of employment.
This sort of two-tier system seems to have its counterpart in the world.
Although the current analysis indicates that those who find jobs will always

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leave the firm, the reason is that no adjustment costs are incurred when
hiring new workers. If there were adjustment costs (or firm-specific human
capital), not all of the workers who found jobs would leave the firm.
It should be noted that since every worker who receives an outside job
offer is allowed to accept the offer, the assumption that firms have the power
to tax workers who 1,eaveis no longer necessary. Equation (3) assumes that
the severance payment to workers who receive job offers might be negative.
Since

y2,

cl'(X), and 7l are all positive and Of1(.) 2 B, the

optimal contract implies that sl(0)

> sq(0).

The intuition

behind this result is straightforward. Consider the optimal contract when
workers are risk neutral. In this case, production efficiency results and
workers are paid the value of their marginal productivity in every state of
the world. Workers would earn Of'(.) in all states of nature (B when '6 <

B,,

and w' when B > OH).

The first-period wage would be chosen so that

firms earn zero expected profits. With risk-averse workers, firms trade off
the incentives of providing on-the-job search with insurance against wage
changes. First-period wages would be reduced in order to smooth second-period
earnings; that is, sl(0) > sq(0).

Otherwise, it would be

preferable to keep the contract that resulted when workers were risk neutral,
since it also provided the proper incentives for on-the-job search.
When the assumption that firms can observe which workers receive job
offers is dropped, the above contract must be modified to make it
incentive-compatible. The reason is that the severance payment offered to
workers who find alternate employment is less than the one offered to workers
who are laid off. The following incentive-compatibility constraint reflects
the constraint necessary to prevent workers with outside offers from accepting
these offers during bad states of nature:

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The condition implies that firms first ask workers to reveal whether they
received a job offer. To induce workers to tell the truth, the expected
utility of a worker who admits to receiving a job offer must be greater than
the expected utility of a worker who does not admit to receiving a job offer.
In particular, when l(0)

=

0, the above constraint is always satisfied.

However, when l(0) is near one (that is, when a large fraction of the
labor force is being laid off), the above constraint is not satisfied. To
make the above contract incentive-compatible, severance payments to quits and
layoffs must be equal when l(8)

=

0. This restriction implies that there

will be involuntary unemployment during bad states of nature. The next
section solves for the optimal contract when the firm cannot observe both a
worker's search intensity or whether a worker receives a job offer.

IV. Involuntary Layoffs
Although the assumption that firms can hire additional labor in the second
period is not necessary for the following results, it will be maintained in
this section. Since firms cannot monitor which workers receive job offers,
the optimal contract in the previous section may not be incentive-compatible.
For the following contract it will be assumed that either w2 < w', or that
the firm can restrict the mobility of job-finders by taxing them when they
leave. The optimal contract with an additional incentive-compatibility
constraint is to choose (wl(B), wz(t9),

sq(e), sl(B), q(B),

1(6'),

A , n(0))

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to maximize expected utility subject to the constraint of nonnegative profits,
the incentive-compatibility constraints, and the restriction that employment
be nonnegative:

The first-order conditions can be characterized by the following
equations:

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1
(5)

q(8)

=

q*(B)
0

if

w(e) -

where

W(0)

-

Bfl([A(l-q*(B)+(l-A)(l-l)]N+n(B))

if

W(0)

-

Bfl([l-(1-A)l]N+n(O))

eft
((1-A) [1-1(e) ]N+n(B))

>0
=

0

<0

where
W(8)

=

w'

+

1
l(8)

(6)

=

- U(w2) - U' (wl+sq)
[(wl+s,)

(U(w'+s,)

-

-

w2]) / U 1(wl+sq)

K(8)

where

K(d) - Of' ([A(l-q(B)+(l-A) (l-l*(B)) IN+n(B))

if

K(0)

1*(8)
0

-

8f1(X(1-q(B)+n(B))

<0

if

Bfl((l-Xq(B))N+n(B))

=

<0

where
K(8)

=

B + (1/U1(w2)[U(B+sl(fi)) - U(w2(e))I

-

a

(7)

n(8)

=

n*(B)

o

[B+sl-w,]+ U' (w2)[U(B+sl)

-

U(w'+sl (4))

II

if

w'

-

Bfl(w) > 0

where

w'

-

Bf'(A(1-q(B)+(l-A) (1-1(B))]N+n*(B))

if

w1

-

efl(~(l-~(~>+(I-A)(~-~(B))IN)
<o

From equations (5),

( 6 ) , (7), and (8) we obtain:

q(8)

=

1, l(8) > 0, n(8)

=

0 when '6 < BL

q(0)

=

1, l(8)

=

0, n(B)

=

0 when BL < 8 < OH

q(8)

=

1, 1(B)

=

0, n(8) > 0 when 0 > BH

=

0

0

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where B,fl ([l-X]N)

=

B, BHfl([l-X]N)

=

w' .

The solution to this problem is identical to that given in the previous
section except for the inclusion of the costate variable, -y3(8), which
becomes binding in "bad enough" states of nature. It can be shown that when
-y3(B)

> 0, the severance payment offered to departing workers increases,

while the wage offered to job stayers and the severance payment to laid-off
workers decreases. In addition, there will be fewer layoffs than in a
Walrasian market or overemployment. This occurs when a large fraction of a
given cohort of workers is being laid off. When productivity is high enough
or, equivalently, when there are few layoffs, the incentive-compatibility
constraint holds and -y3(8)
-y3(B)

=

0. However, when productivity is low,

must be greater than zero for the incentive-compatibility constraint

to hold. Since q(B)

=

1, when B

< BL the incentive-compatibility

constraint becomes

In order for workers to engage in on-the-job search in the first period,
we know that w1+sP(B) > w2(B) .

Hence the above constraint fails when

1(B) is near one. Four margins of adjustment occur in order for the
incentive-compatibility constraint to hold: First, from ( 6 ) , since U(C) is
concave l(0) must decrease, that is, there is overemployment. Second,
from (b) and (d),

both w2(B) and sl(B) must decrease. Finally,

from ( 3 ) , sq(B) must increase. These adjustments occur when -y3(8) is

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positive. If y3(B) were negative, the incentive-compatibility constraint
would be violated.
Involuntary unemployment occurs when a large fraction of the firm's labor
force is laid off. This condition seems particularly strong; however, it does
not seem unreasonable if the condition is interpreted to be a plant closing.
The model predicts that severance payments to both quits and layoffs will
be state-independent except during downturns. During severe downturns, the
severance payment or bonus offered in the first phase of the labor-force
adjustment will actually increase, so that workers who find jobs will
truthfully reveal their job offers. In addition, during these downturns the
severance payments to laid-off workers will decrease so that they are
involuntarily laid off.

V.

A Two-Sector Implicit Contracting Model
This section extends the analysis of the previous sections by explicitly

modeling the second sector. Instead of assuming that job-finders receive a
wage exogenously given to be w', workers who switch sectors enter a spot
market and are paid their marginal productivity. It is shown that a
two-sector implicit contracting model helps explain why quits are procyclical.
Each sector of the economy has many identical firms. Both sectors are
identical in period one, but differ according to the technological shock
affecting their sector in the second period. The first-period production
function for sector A and sector B is given by F(NIA) and F(NIB),
respectively. In the second period there is a shock to production, BA and

BB, where 9' denotes the vector (BA, dB).

The second-period

production function for sector A firms is given by BAf(NA), while the
production function for sector B firms is given by BBf(N,,).

It is

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assumed that BA and BB are independent and have the same density
function, g(BA) and g(BB).

At the beginning of period two, everyone can

costlessly observe the state of nature 8'.
The economy is inhabited by 2N agents. Due to industry- or
sector-specific human capital, which agents acquire by working in a sector
during the first period, an agent cannot work in the other sector during the
second period without additional training. For a worker in sector A [B] in
the first period to be productive in sector B [A] in the second period, he
must expend a cost c(AA) [c(AB)].

However, training is not perfect; a

worker who undergoes training may or may not learn the skills necessary to
switch sectors. A first-period employee of sector A [B] is successful in his
attempt to be productive in the other sector with probability XA [AB].
Workers must undertake this investment in period one before the realization of
8, and OB.

A worker's skills are not left entirely to chance. A worker can increase
the probability that he will be productive in the other sector by spending
more on training in the first period. That is, the more a worker invests in
learning the skills of the other firm (the higher is c(Xi) i=A,B), the
greater the probability that he will become productive in the other sector
(the larger is Xi).

The same restrictions as earlier are placed on

c(X,>.

A worker who learns the skills necessary to work in the other sector may
or may not receive a job offer to work in that sector. A worker in sector A
[B] who is also productive in sector B [A] receives a job offer from that
sector with probability hB(B1) (hA(B1)), where hA(B1) and hB(B1)
are chosen by firms A and B, respectively. Therefore, XAhB(B1) is the
probability that a worker in sector A will receive an offer to work in sector

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B. However, as in the previous sections, only a fraction, qA(B'), (chosen
by firm A) of these workers will be hired by sector B.
A worker currently working in sector A who is hired by sector B receives a
wage, ~'~(0'). Since this wage is determined in a spot market,
second-period wages must equal the worker's marginal productivity, wtB(B')
=

0Bf'(N2B).

competition for workers who change jobs ensures that

firm
~ A chooses a
this equality holds. In addition to a wage of ~ ' ~ ( 0 ' )
severance payment of sPA(B1) to pay its departing workers.
Unlike the previous section, which tried to rationalize the existence of
involuntary layoffs, this section is not concerned with whether a layoff is
voluntary or involuntary. Thus, we will keep the assumption of section I11 by
assuming that a firm can observe whether a previous employee starts work at
another firm and thus can condition its severance payment on this realization.
We also assume that firms can observe which sector an ex-employee works for
and can condition its severance payment on this realization. Since all firms
in a given sector are identical, firms do not give severance payments to
workers wishing to work in the same sector. In fact, the contract may call
for the firm to tax workers to prevent them from working at a
different firm within the same sector. Because there is no benefit to working
at a different firm within the same sector, the optimal contract does not
allow for that possibility. These assumptions allow us to model the problem
as if each sector were comprised of one representative firm.
The analysis assumes that firms do not have implicit contracts with the
workers in the alternate sector. Otherwise, in period one, a firm in sector A
would promise a second-period wage (conditional on 0') to workers in sector B
who wish to switch sectors. Firms would do this in order to induce workers in
the other sector to acquire the skills necessary for work in their sector.

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However, by assuming that each sector consists of many identical firms, no one
firm would have an incentive to make such a promise: it would not change the
incentive for workers in the other sector to engage in on-the-job training.
Given these restrictions, second-period employment for a firm in sector A
and a firm in sector B is given by the following equations:

As in the previous sections, a worker signs a contract with his firm
specifying the second-period wage, the severance payments, and separation
probabilities contingent on the state of nature in the second period, O', as
well as on the first-period wage. Contracts are chosen in the first period to
maximize the utility of the representative worker subject to a given level of
profits and the incentive-compatibility constraint.
Firms are assumed to be Nash competitors; they assume that their choice of
a contract has no effect on the contract offered by the other firms (the other
sector).

cwU,

The optimal contract for firm A is then to choose

~ ~ ~ ( ,0 ~'~(0')
')
, lA(el> qA(el),

sBA(O1), hA(B'), XA) to maximize

slA(e')

9

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The first-order conditions can be characterized by the following equations
(1) U'blA)

=

7,

1
(5a)

q(0')

=

q*(el 1

0
where

if

w(el) -

efl(N,)

>

0

if

w(el) -

eft(N,)

=

o

efl(N,)

<

0

if W(el)

-

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W(B1)

=

w',

+
-

(U(wl,+sq)

-

U(wZA)

U' (wtB+sqA)
[ (wrB+sqA)- wZA])/Ur(wrB+sqA)

Since sector B is identical, the following consistency conditions must
also hold (all variables are taken to solve the preceding first-order
conditions):
1,(OA, 0,)

=

1,(B,,BA)

q,(B,,B,)

=

qB(BB,BA)

hA(BA,BB) = hB(BB,BA) wZA(BA,BB) = wZB(BB,BA)
slA(BA,BB)= slB(BB,BA),sqA(BA,BB)= sqB(BB,BA)
WIA =

wlB,A,

=

A,, hB(efl(~,,)

-

wl(el)) = 0.

The following equations summarize the dynamics of the system. Because of
the above consistency conditions, we denote i, j

=

(A, B) where i

0 < li(B1) < 1, qi(Br) = 1, hi(Br) = 0

when 8, 2 BL(Bj)

li(er) = 0, qi(et) = 1, 0 < hi(Br) < 1

when BL(Bj)

< Bi 5 B,(Bj)

li(Br) = 0, qi (0')

when BM(Bj)

< Bi 5 BH(Bj)

=

1, hi(B1) = 1

li(Br) = 0, 0 < qi(B') < 1, h,(B1)

=

1

when

Bi > BH(Bj)

=

j.

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BM(Bj),

OL(Bj),

BL(Bj)

O,(Bj)

are determined as follows:

solves BL(ej)fr ([1-Xhj(Oj ,OL) INlj)= B

where

h(O

eL)

j,

=

0

if

Bjfr(N,)

indeterminate

if

Bj

0,

if Bjfr([l+X]Nl)

1

dM(Bj)

=

- B<O

solves 8,(dj)fr

- B > 0.

([~+A[~(B~
,B~)-~(~~,o,])N')= B

where
q(ej,oM)

=

1, h(ej,eM)

=

0

if ejfr([l-X)(l-l(dj,OL)) IN1)

=

B

for some 0 < l(O,,BM) < 1

q(dj,O,)

=

1, h(ej,oM)

h(Oj,0,)

=

1, 0 < q(Bj,BM) < 1

=

1

if ejft
(N,)

5

w(BA, 0,)

if Bjfr([l+X(l-q(Bj,B))]N1)
for some 0 < q(Bj,BM) < 1

q(Bj,BM)

if Ojfr([l+X]Nl) > W(BA,BB)

=

0, h(Bj ,OM)

=

w', + (U(wrB+sqA)- u(wZA)

=

1

where
W(dA, 0,)

- ur(wrB+sqA)[ (w'B+sqA) - wZAl )/Ur(w'B+sqA)
and

=

W(BA,O,)

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BH(Bj)

solves BH(Bj)ft ([l+X(l-h(ej, eH))IN1)

where h(Bj,BH)

=

=

W(eA,eB)

h(ej,BH).

The above conditions imply that the following hold:

(2a)

U'(W,~(B'))

(2b)

U'(w2,(B1))

71i1hXi

=

(Xi+7,,)

=

for 8,

71i(l-hjAiqi(e'1)
a-hj(Ai+72i) 1

< 8,(Ot)

for

ei >

e,(et).

The model predicts that quits can occur in equilibrium even when the
productivity shocks in the two industries are identical. This contrasts with
a Walrasian model where the number of quits depends on the dispersion of the
productivity shocks across sectors. The model also predicts that quits will
generally be procyclical. For example, if Oi

=

Bj and if demand is low

in both sectors, no quits occur, because neither industry is willing to hire
workers from the other industry. As productivity in both industries gets
progressively better, quits increase discontinuously from 0 to 2X. That is,
quits increase until everyone who is productive in the other sector switches
sectors. This discontinuity results from the assumption that the shocks to
the two sectors are identical, Bi

-

Bj. As soon as industry A and

industry B find it profitable to hire a worker from the other industry, each
will then find it profitable to hire one more worker to replace the worker who
shifted sectors. This process continues until h

=

1.

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When the shock increases in only one sector, this discontinuity does not
occur. When the sector with the good technological shock finds it profitable
to hire a worker from the other sector, the low-shock sector will respond by
laying off one fewer worker. Thus, the model also predicts that there should
be more layoffs within each industry (or that layoffs will occur sooner) if
both B, and B j are low rather than if there is a downturn that is
confined to only one sector.
While the model in general predicts that quits should be procyclical,
quits may start decreasing when productivity increases in only one of the
sectors. This occurs when demand is unusually high in only one of the
sectors, so that the sector will find it profitable to retain workers instead
of letting them quit, q < 1. The model has a bias toward quits because of the
need to promote on-the-job training. However, when the technology shock to a
particular industry is very high, this bias is not as important as the need to
retain workers. When productivity increases in both sectors, this turning
point does not occur, because the incentive to let workers quit is greater,
the more the other sector pays to newly hired workers.
Wages respond as follows: second-period wages for those who stay with
their original firm depend on the state of nature in both sectors. From (2a)
and (2b), wages either decrease or remain constant when the other sector
becomes more productive, and wages increase (or remain constant) with
increases in the productivity affecting their own sector.
These wage changes result from the need to promote on-the-job training.
The more people who switch sectors, the greater the effect (ex ante) of a high
wage differential between those who switch sectors and those who stay. Thus,
the higher the shock affecting sector B, the lower the wage that will be paid
in sector A to job stayers. Similarly, when the technological shock to

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industry A is very high, fewer workers will switch sectors and, thus, higher
wages will be paid to job stayers.
Severance payments to quits increase with the wage paid by the other
sector, so that the wage plus severance payment is constant over all states of
nature. This implies that if one wanted to generate involuntary layoffs in
this two-sector model, the productivity shock would have to be very low in one
of the sectors and quite low in the other sector. This corresponds to job
finders receiving a very low severance payment and a large chance that they
would be laid off with a larger severance payment if they did not admit to
receiving a job offer.
This analysis suggests that one way to generate involuntary layoffs is for
job finders to want to pretend that they did not receive a job offer in order
to collect the severance payment to laid-off workers. That is, involuntary
unemployment can be explained by understanding why severance payment to quits
is low. This might occur if the informational restrictions of this section
were loosened. For example, it has been assumed that an employer could
observe whether or not a worker quit to accept a job in the same sector. If
employers could not observe whether this occurred, then severance payments
would have to be restrained to prevent workers from switching jobs within the
same sector.

VI. Conclusions
This paper builds a two-sector implicit contracting model in order to
investigate the conditions under which involuntary unemployment can result and
to help understand why quits are procyclical. The results are encouraging:
under certain conditions quits can be procyclical and layoffs can be
countercyclical, and some layoffs may be involuntary. To achieve this result,

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the conditions were that firms cannot observe a worker's search/training
intensity and that firms cannot monitor which workers receive job offers.
Involuntary unemployment results in order to induce workers to reveal
successful search efforts.
The paper also shows that firms will have a two-tier procedure for
adjusting their labor force to current economic conditions. In the first
round, workers with outside offers leave the firm; in the second round, the
firm adjusts its labor force by either laying off additional workers or hiring
new workers. The model implies that workers will leave firms in sector A for
firms in sector B, and at the same time, firms in sector A will hire
additional workers from sector B. This occurs because firms have to offer
contracts in order to give workers incentives to engage in on-the-job
search/training.

This implies that firms subsidize workers when they leave,

and they let workers leave more often than would happen in a Walrasian market.
One frequent criticism of the above analysis is the implication that firms
are subsidizing workers to engage in more on- the-job search/training. Ex ante
contracts will be chosen so that workers will find it optimal to engage in
such search activity; however, ex post, it would not be surprising to think
that firms are in some sense antagonistic to such activity. Firms will, of
course, wish that none of their workers are successful in their job search.
Similarly, another way of thinking about the problem is that firms sign
contracts that reduce worker mobility in order to partially insure workers
against income changes.
This paper shows why complete insurance to laid-off workers would not be
optimal, given the incentive-compatibility constraints. Additional empirical
work is necessary to answer the question of whether the amount of severance
payments predicted by models such as this occurs in the world. State-mandated

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unemployment benefits are one reason that the amount of severance payments
offered by firms might not be that extensive. Theory suggests that the two
are substitutes; thus, increases in state-provided unemployment insurance
should decrease private severance-payment programs. Future empirical work can
be conducted to see if privately financed unemployment benefits decrease with
increases in state-provided unemployment insurance.

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