A choice reveals only what the menu separates¶
Cross-Domain EchoesShared pattern · Incentive Compatibility
An airline can trade a lower fare for advance-booking and stay restrictions. An insurer can trade a lower premium for a larger deductible. In each hypothetical menu, the designer wants a private difference to become visible through choice rather than a self-description. The diagram shows the intended separating choices, not observed facts about all travelers or drivers. Each arrow needs its own best-response check: would this type prefer its displayed option over the other one? If both types prefer the same offer, the menu no longer reveals the distinction. Wealth and liquidity can also make a menu sort a different attribute from the one its designer intended.
Choose a role to see its counterpart in both examples. The diagrams show relationships, not measured quantities.
Airline fare design
A fare fence prices flexibility
Read Screening Menu or Self-SelectionMechanism
A hypothetical fare menu makes different restrictions differently attractive to traveler types.
In this example: Travel purpose does not fix wealth or schedule flexibility; the sort is imperfect.
Auto-insurance contract design
A deductible changes the expected cost
Read Self-Selection MenuMechanism
A hypothetical premium/deductible menu can make privately different claim risks choose different plans.
In this example: Ability to bear the deductible can affect the choice as well as expected claims.
These are different payoff-relevant attributes, not moral labels.
Written comparison
The private distinction
Airline fare design
Value of schedule flexibility
Auto-insurance contract design
Expected claim risk
These are different payoff-relevant attributes, not moral labels.
A designed tradeoff
Airline fare design
Price versus travel restrictions
Auto-insurance contract design
Premium versus deductible
The offers must be valued differently by the intended types.
The best-response requirement
Airline fare design
Neither traveler type gains by mimicking the other
Auto-insurance contract design
Neither risk type gains by choosing the other intended plan
The drawing is a proposed separating case; both off-diagonal alternatives still need checking.
What carries across
Check both types against both options. A menu reveals information only if the intended choices are actually better for the respective participants.
Where the comparison stops
This is a hypothetical mechanism-design comparison, not current airline pricing or insurance advice.
- Separation is not fairness, efficiency or perfect classification. A menu may sort wealth or liquidity rather than the claimed private trait.
- These cases do not inherit the dominant-strategy truth-telling theorem of a Vickrey auction; they require their own preference and strategy assumptions.
Conditions for this comparison
- Types rank the offered cost-benefit bundles differently.
- Each type prefers its intended option to every available imitation under stated assumptions.
Source entries
Shared pattern
Incentive Compatibility
Prime
Core Idea
*Incentive Compatibility*, in the formulation introduced by Hurwicz (1972), names the design property that (1) a mechanism, rule, contract, or institution is *incentive-compatible* when (2) each participant, acting to maximize their own private payoff, (3) finds that their best response is also the action the designer wanted them to take — most importantly, *truthfully revealing* their private information or *choosing* the socially desired behavior — so that (4) no costly monitoring, enforcement, or exhortation is required beyond the mechanism's native structure.
Airline fare design
Screening Menu or Self-Selection
Mechanism
Example
A cheap fare requires booking weeks ahead and staying over a Saturday night; a costly fare carries neither restriction and allows free changes.
How it works
Space the terms so each type strictly prefers its intended option and gains nothing by imitating the other
When it helps, and when it misleads
sorting on ability to bear a cost rather than the intended trait
Auto-insurance contract design
Self-Selection Menu
Mechanism
Example
Plan A carries a high deductible and a low premium; Plan B carries a low deductible and a high premium.
When it helps, and when it misleads
a menu that sorts on willingness to bear cost may reveal wealth rather than the intended type