Concept Architecture
Concept
Theoretically, Screening Theory explains how a less-informed party designs mechanisms to induce better-informed individuals to reveal private information through their choices. It is a central component of information economics and contract theory, addressing problems of adverse selection arising from asymmetric information. The theory exists to enable principals to distinguish between heterogeneous agents when individual characteristics cannot be directly observed.
Mathematically, screening theory is represented as an optimisation problem in which the principal designs a menu of contracts, prices or options that maximise expected utility or profit subject to participation and incentive compatibility constraints. The mathematical framework ensures that each agent voluntarily selects the contract intended for their underlying type, thereby revealing private information through self-selection.
In practice, screening theory is implemented through insurance benefit design, provider contracting, reimbursement mechanisms and health programme eligibility criteria. In health economics, insurers use deductibles, copayments and coverage options to encourage individuals with different risk profiles to self-select appropriate insurance products. Screening models are also applied to procurement, pharmaceutical pricing and provider payment systems where information asymmetry influences market outcomes.
Purpose
Used to analyse adverse selection, design self-selection mechanisms, develop incentive-compatible contracts, evaluate insurance benefit structures, and improve resource allocation under asymmetric information.
Mathematical Formulae
Primary Formula
The principal's optimisation problem:
max?C(?)? E[U?]
subject to
Participation constraint:
U?(C(?), ?) � U?
Incentive compatibility constraint:
U?(C(?), ?) � U?(C(??), ?)
where:
- C(?) = contract designed for type ?
- ? = agent type
- U? = principal utility
- U? = agent utility
- U? = reservation utility
Supporting Formulae
Expected utility:
E(U) = ? p?U(x?)
Self-selection condition:
?? ? C?
through voluntary contract choice satisfying the incentive compatibility constraints.
Related Mathematical Methods
- Mechanism design
- Contract theory
- Expected utility theory
- Constrained optimisation
- Game theory
- Information economics
Example
A health insurer offers two insurance plans. Plan A has a low premium with a high deductible, while Plan B has a higher premium with comprehensive coverage. Individuals expecting low healthcare utilisation tend to choose Plan A, whereas individuals anticipating higher utilisation select Plan B. The insurer uses screening theory to design the contracts so that individuals reveal their underlying risk through voluntary self-selection rather than direct disclosure.
Excel Implementation
| Function | Example Formula | Health Economics Application |
|---|---|---|
| SUMPRODUCT | =SUMPRODUCT(B2:B10,C2:C10) | Calculate expected insurer costs or utilities |
| IF | =IF(E2>=F2,""Constraint Satisfied"",""Constraint Violated"") | Check participation or incentive compatibility constraints |
| MAX | =MAX(B2:B10) | Identify the preferred contract for each individual type |
| Solver | Solver optimisation | Optimise contract parameters subject to incentive constraints |
VBA (Optional)
Automate evaluation of alternative insurance contract designs while testing participation and incentive compatibility constraints across multiple population risk groups.
Sources
- Rothschild M, Stiglitz JE. Equilibrium in Competitive Insurance Markets: An Essay on the Economics of Imperfect Information. Quarterly Journal of Economics. 1976.
- Laffont JJ, Martimort D. The Theory of Incentives: The Principal-Agent Model. Princeton University Press.
- Bolton P, Dewatripont M. Contract Theory. MIT Press.
- Arrow KJ. Uncertainty and the Welfare Economics of Medical Care. American Economic Review. 1963.
- Drummond MF, Sculpher MJ, Claxton K, Stoddart GL, Torrance GW. Methods for the Economic Evaluation of Health Care Programmes. Oxford University Press.
Related Concepts (2)
Frequently Asked Questions (6)
What is screening theory?
A body of theory analysing how an uninformed party can design a menu of options that leads individuals to reveal their private information through choice.
Source: Rothschild & Stiglitz 1976
Who developed screening theory?
The analysis of screening was developed by Michael Rothschild and Joseph Stiglitz, who showed how a party lacking information could design a set of options that leads the informed party to sort itself. In their insurance model, offering a choice between full cover at a high price and partial cover at a low one leads high and low risks to pick different contracts, revealing their type through the choice. The uninformed party thus learns indirectly what it cannot observe. Rothschild and Stiglitz (1976) set out the theory.
Source: Rothschild & Stiglitz 1976
How does screening work?
Screening works by offering a menu of options designed so that each type of person finds it in their interest to choose the option intended for their type, thereby revealing their private information through their choice. The options are structured to exploit the differences between types, so that, for example, high and low risks prefer different insurance contracts. The uninformed party learns each person's type from which option they select, without needing them to declare it directly.
Source: Rothschild & Stiglitz 1976
How does screening differ from signalling?
Screening and signalling both address information asymmetry but differ in who acts. In screening, the uninformed party takes the initiative, designing a menu of options that induces the informed to reveal their type through choice. In signalling, the informed party takes the initiative, undertaking a costly action to convey their private information credibly. Screening is the uninformed drawing out information; signalling is the informed sending it. Both can sort types, but they place the initiative on opposite sides of the transaction.
Source: Rothschild & Stiglitz 1976
How is screening used in insurance?
Screening is used in insurance by offering a menu of contracts that sorts buyers by risk. An insurer unable to observe individual risk offers, for example, a contract with full cover at a high premium alongside one with partial cover at a lower premium, structured so that high risks choose the former and low risks the latter. Buyers reveal their risk through their choice, allowing the insurer to price accordingly. This is the screening solution Rothschild and Stiglitz analysed.
Source: Rothschild & Stiglitz 1976
What are the limitations of screening?
Screening has limitations. To sort types, the options offered to some, typically the low risks, must be worse than they would receive under full information, so screening imposes a cost on them, such as incomplete insurance. A stable screening outcome may not exist in a competitive market, as Rothschild and Stiglitz showed. Screening also requires that types differ in ways the menu can exploit, and it depends on the uninformed party being able to design and commit to the options.
Source: Rothschild & Stiglitz 1976
Trust Record
Verified by Dr Darrin Baines
British health economist
Professional identity: darrinbaines.org
Verification date: 12 Sep 2025
Content version: 1.0.0
Canonical Identity
- Persistent URI
- https://healtheconomics.wiki/concept/screening-theory
- Term code
- HE-EE-ME-064
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