Asymmetric Information
In one line. Asymmetric information exists when one party to a transaction knows more than the other. It causes adverse selection before the contract, from hidden type, and moral hazard after it, from hidden action, each a route to market failure. This is H2 only.
Exam relevance: the highest-yield micro theme, market failure and its correction appear almost every year, on ETG analysis. Taught the way an economics tutor who wrote the answer keys teaches it.
01What asymmetric information is
Asymmetric information is a situation where one side of a deal knows more than the other, and it is an H2 cause of market failure that works through two distinct channels.
Asymmetric information exists when one party to a transaction has more or better information than the other, producing adverse selection before the contract and moral hazard after it.
This page is H2 only. H1 students cover general information failure but not adverse selection or moral hazard.
02Adverse selection
Adverse selection happens before a contract is signed, when the side that knows its own hidden type selects in, worsening the pool for everyone.
In health insurance, the insurer cannot see who is high risk. If it charges one average premium, low risk people find it poor value and leave, while high risk people buy in. The pool worsens, premiums rise, more low risk people leave, and the market can spiral toward collapse.
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03Moral hazard
Moral hazard happens after a contract, when being covered changes behaviour in a way the other party cannot observe.
Once insured, a person may take more risk or over use care, ordering tests they would not pay for themselves, because the cost falls on the insurer. The hidden action raises claims and premiums, another route to market failure.
04Not the same as imperfect information
Keep asymmetric information separate from general imperfect information.
Imperfect information means everyone lacks full information. Asymmetric information means one side knows more than the other, and it is that imbalance, not ignorance in general, that drives adverse selection and moral hazard.
05Common misconceptions
Place the two failures in time: adverse selection before the contract (hidden type), moral hazard after it (hidden action). Swapping them is the most common error, and do not blur either with plain imperfect information.
06Test yourself
- Explain how adverse selection can cause a health insurance market to unravel.
- Give an example of moral hazard and explain why it raises premiums.
07Questions students ask
Asymmetric information exists when one party to a transaction has more or better information than the other. It is an H2 topic and produces two distinct failures, adverse selection before the contract and moral hazard after it, each of which can make a market break down.
Adverse selection happens before the contract, from hidden type: the better informed party self selects in, for example high risk people buying the most insurance, which worsens the risk pool. Moral hazard happens after the contract, from hidden action: being covered changes behaviour, for example the insured taking more risk.
No. Asymmetric information, adverse selection and moral hazard are H2 only content; H1 students study general information failure but not these. Knowing the boundary saves H1 students from spending time on material that cannot be examined.