Work
In Progress:
Non-exclusive Dynamic Contracts,
Competition,
and the Limits of Insurance
(joint
with Laurence
Ales)
We study how the
presence of non-exclusive contracts limits the amount of
insurance provided in a decentralized economy. We consider a
dynamic Mirrleesian economy in which agents are privately
informed about idiosyncratic labor productivity shocks. Agents
sign insurance contracts with multiple firms (i.e., they are
non-exclusive), which include both labor supply and savings
aspects. These contract arrangements are private information.
Firms have no restriction on the contracts they can offer,
interact strategically, and, as in common agency problems,
might offer latent contracts to sustain
equilibrium allocations. In equilibrium, contrary to the case
with exclusive contracts, a standard Euler equation holds, and
the marginal rate of substitution between consumption and
leisure is equated to the worker's marginal productivity.
Finally, each agent receives zero net present value of
transfers from insurance providers. To sustain this
equilibrium, more than one firm must be active in offering the
equilibrium allocation. Each active firm must also offer
latent contracts to deter deviations to more profitable
contingent contracts. In this environment,
the non-observability of contracts removes the possibility
of additional insurance beyond self-insurance. To test the
model, we allow firms to costly observe contracts. The model
endogenously divides the population into agents that are not
monitored and have access to non-exclusive contracts and
agents that have access to exclusive contracts. We use US
household data and find that high school graduates satisfy the
optimality conditions implied by the non-exclusive contracts
while college graduates behave according to the second group.
Accounting for Private Information
(joint with Laurence
Ales)
We study the quantitative properties of
constrained efficient allocations in an environment where risk sharing
is limited by the presence of private information. We consider a
lifecycle version of a standard Mirrlees economy where shocks to labor
productivities have a component which is public information and one
which is private information. The presence of private shocks has
important implications for the age profiles of consumption and income.
First, they introduce an endogenous dispersion of continuation
utilities. As a result consumption inequality rises with age even
though the variance of the shocks does not. Second, they introduce an
endogenous rise in the covariance between consumption and income over
the lifecycle. This is because, as agents age, the ability to properly
provide incentives for work must become less and less tied to promises
of benefits (through either increased leisure or consumption) in future
periods. Both of these features are also present in the data. We look
at the data through the lens of our model and estimate the fraction of
labor productivity that is private information. We find that for the
model and data to be consistent, a large fraction of shocks to labor
productivities must be private information.
Skill,
luck and information: private information as a source of lifetime
inequality
(joint with Laurence
Ales)
Data
on consumption inequality is inconsistent with models with full risk
sharing. Recent literature has addressed this fact by introducing
market incompleteness or limited commitment. In this paper we focus on
an alternative channel to generate consumption inequality. We consider
an environment in which private information is the main friction. We
focus on two sources of private information, one permanent and one
temporary. The first is learning ability which is draw once and for all
before entering the labor market. We assume that learning ability
affects the workers' productivity only through the accumulation of
human capital. Labor productivity is also affected by a temporary shock
which is the second source of private information. We solve for the
information constrained optimal allocation for this environment and
compare it with the distributions of consumption, income and hours in
the US data. This approach allows us to study the joint determination
of income and consumption and to look at the implication for
conditional moments of these two variables. The private information
nature of the productivity shock allows us to match the overall change
in consumption variability over the lifecycle while also being
consistent with the decline of conditional income variance with age.
Models with incomplete markets that specify an exogenous income process
cannot match this feature of the data. In our environment differences
in learning abilities generate permanent consumption inequality early
in life. The increase in inequality over the lifecycle is necessary to
provide incentives to reveal the idiosyncratic productivity shock.
Preliminary results indicate that differences in learning ability are
more important when accounting for consumption inequality.
Efficient Allocations with
Limited Commitment
(joint with Roozbeh
Hosseini)
We
study the social insurance problem in an environment where agents
have private information about their taste shocks and the insurance
provider (or government) cannot commit to the ex ante optimal
allocation rules. With no commitment, the government is tempted to use
updated beliefs about agents’ types and offer a new insurance
plan each
period. Given this lack of commitment, we allow the government to use a
general communication mechanism (as opposed to direct communication).
In this communication system, agents report their type to a mediator,
and the mediator sends a (possibly random) signal of the types to the
government. We show that in this setup the revelation principal holds
and agents’ behavior can be summarized by a set of incentive
compatibility constraints. This allows us to write the problem of
finding the efficient allocation as a maximization problem subject to a
set of incentive and feasibility constraints and a series of time
consistency constraints. In general, the optimal allocation rules in
environments with noisy communication (with mediator) might be
different from the ones with direct communication. Every optimal
allocation under direct communication can be implemented by a noisy
communication system, however, the converse is not always true. We use
this set up to investigate this issue and provide a simple example in
which the optimal allocation is indeed different under both
communication system.
Adverse
Selection and Non-exclusive Contracts
(joint
with Laurence Ales)
This
paper studies the Rothschild and Stiglitz (1976) insurance environment
relaxing the assumption of exclusivity of insurance contracts. Agents
can engage in multiple insurance contract simultaneously and the terms
of these contracts are not observed by other firms. Insurance providers
behave non-cooperativelly and compete offering menus of insurance
contracts from an unrestricted contract space. We show that the
Rothschild and Stiglitz equilibrium allocation is not an equilibrium in
the presence of non-exclusive contracting, since firms will offer
latent contracts to prevent deviation by other firms that prevent
separation of the agents. This possibility also implies that latent
menus can prevent cream-skimming strategies, however pooling
equilibrium still fails to exists. We derive the conditions under which
a separating equilibrium exists and fully characterize it. The
equilibrium allocation consists of agents with a lower probability of
accident purchasing no insurance and agents with higher accident
probability buying the actuarilly fair competitive level of insurance.
To sustain the equilibrium allocation firms must offer latent
contracts. The equilibrium allocation also constitute a linear price
schedule for insurance.
Publications:
A Model of Banknote Discounts
(joint
with Laurence
Ales, Francesca
Carapella, Warren
Weber)
Journal
of Economic Theory, vol. 142, Issue 1, September 2008, pg. 5-27
Prior
to 1863, United States banks issued notes---dollar-denominated promises
to pay specie on demand. Banknotes circulated at par locally but at a
discount outside the local area. Discounts varied by bank location and
the location of the discount quote and were asymmetric across
locations.
Discounts increased when banks suspended payments. In this paper we
construct a random matching model to qualitatively match these facts.
The model has nonbankers and bankers in each of two locations. Bankers
issue and redeem notes that serve as media of exchange. The model
delivers predictions consistent with the discount facts.
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