Concept in contract theory and economics
In contract theory, mechanism design, and economics, an information asymmetry is a situation where one party has more or better information than the other.
Information asymmetry creates an imbalance of power in transactions, which can sometimes cause the transactions to be inefficient, causing market failure in the worst case. Examples of this problem are adverse selection, moral hazard, and monopolies of knowledge.
A common way to visualise information asymmetry is with a scale, with one side being the seller and the other the buyer. When the seller has more or better information, the transaction will more likely occur in the seller's favour ("the balance of power has shifted to the seller"). An example of this could be when a used car is sold, the seller is likely to have a much better understanding of the car's condition and hence its market value than the buyer, who can only estimate the market value based on the information provided by the seller and their own assessment of the vehicle. The balance of power can, however, also be in the hands of the buyer. When buying health insurance, the buyer is not always required to provide full details of future health risks. By not providing this information to the insurance company, the buyer will pay the same premium as someone much less likely to require a payout in the future. The adjacent image illustrates the balance of power between two agents when there is perfect information. Perfect information means that all parties have complete knowledge. If the buyer has more information, the power to manipulate the transaction will be represented by the scale leaning towards the buyer's side.
Information asymmetry extends to non-economic behaviour. Private firms have better information than regulators about the actions that they would take in the absence of regulation, and the effectiveness of a regulation may be undermined. International relations theory has recognized that wars may be caused by asymmetric information and that "Most of the great wars of the modern era resulted from leaders miscalculating their prospects for victory". Jackson and Morelli wrote that there is asymmetric information between national leaders, when there are differences "in what they know [i.e. believe] about each other's armaments, quality of military personnel and tactics, determination, geography, political climate, or even just about the relative probability of different outcomes" or where they have "incomplete information about the motivations of other agents".
Information asymmetries are studied in the context of principal–agent problems where they are a major cause of misinforming and is essential in every communication process. Information asymmetry is in contrast to perfect information, which is a key assumption in neo-classical economics.
In 1996, a Nobel Memorial Prize in Economics was awarded to James A. Mirrlees and William Vickrey for their "fundamental contributions to the economic theory of incentives under asymmetric information". This led the Nobel Committee to acknowledge the importance of information problems in economics. They later awarded another Nobel Prize in 2001 to George Akerlof, Michael Spence, and Joseph E. Stiglitz for their "analyses of markets with asymmetric information". The 2007 Nobel Memorial Prize in Economic Sciences was awarded to Leonid Hurwicz, Eric Maskin, and Roger Myerson "for having laid the foundations of mechanism design theory", a field dealing with designing markets that encourage participants to honestly reveal their information.
History.
The puzzle of information asymmetry has existed for as long as the market itself but remained largely unstudied until the post-WWII period. It is an umbrella term that can contain a vast diversity of topics.
Greek Stoics (2nd century BCE) treated the advantage that sellers derive from privileged information in the story of the Merchant of Rhodes. Accordingly, a famine had broken out on the island of Rhodes and several grain merchants in Alexandria set sail to deliver supplies. One of these merchants who arrives ahead of his competitors faces a choice: should he let Rhodians know that grain supplies are on the way or keep this knowledge to himself? Either decision will determine his profit margin. Cicero related this dilemma in "De Officiis" and agreed with Greek Stoics that the merchant had a duty to disclose. Thomas Aquinas overturned this consensus and considered price disclosure was not obligatory.
The three topics mentioned above drew on some important predecessors. Joseph Stiglitz considered the work of earlier economists, including Adam Smith, John Stuart Mill, and Max Weber. He ultimately concludes that though these economists seemed to have an understanding of the problems of information, they largely did not consider the implications of them, and tended to minimize the impact they could have or consider them merely secondary issues.
One exception to this is the work of economist Friedrich Hayek. His work with prices as information conveying relative scarcity of goods can be noted as an early form of acknowledging information asymmetry, but with a different name.
2001 Nobel Prize Inspirations.
Information problems have always affected the lives of humans, yet it was not studied with any seriousness until near the 1970s when three economists fleshed out models which revolutionized the way we think about information and its interaction with the market. George Akerlof's paper "The Market for Lemons" introduced a model to help explain a variety of market outcomes when quality is uncertain. Akerlof's primary model considers the automobile market where the seller knows the exact quality of a car. In contrast, the buyer only knows the probability of whether a vehicle is good or bad (a lemon). Since the buyer pays the same price (based on their expected quality) for good cars and bad cars, sellers with high-quality cars may find the transaction unprofitable and leave, resulting in a market with a higher proportion of bad cars. The pathological path can continue as the buyer adjusts the expected quality and offers even lower prices, further driving out cars with not-so-bad quality. This results in a market failure purely driven by information asymmetry, as under perfect information, all cars can be sold according to their quality. Akerlof extends the model to explain other phenomena: Why raising the insurance price cannot facilitate seniors getting medical insurance? Why may employers rationally refuse to hire minorities? Through various applications, Akerlof developed the importance of trust in markets and highlighted the "cost of dishonesty" in insurance markets, credit markets, and developing areas. Around the same time, an economist by the name of Michael Spence wrote on the topic of job market signaling, and was introduced a work of the same name. The final topic is Stiglitz's work on the mechanism of screening. These three economists helped to further clarify a variety of economic puzzles at the time and would go on to win a Nobel Prize in 2001 for their contributions to the field. Since then, several economists have followed in their footsteps to solve more pieces of the puzzle.
Akerlof.
Akerlof drew heavily from the work of economist Kenneth Arrow. Arrow, who was awarded a Nobel Prize in Economics in 1972, studied uncertainty in the field of medical care, among other things (Arrow 1963). His work highlighted several factors which became important to Akerlof's studies. First, is the idea of moral hazard. By being insured, customers may be inclined to be less careful than they otherwise would without insurance because they know the costs will be covered. Thus, an incentive to be less careful and increase risk exists. Second, Arrow studied the business models of insurance companies and noted that higher-risk individuals are pooled with lower-risk individuals, but both are covered at the same cost. Third, Arrow noted the role of trust in the relationship between doctor and patient. Medical providers only get paid when a patient is sick, and not when a person is healthy. Because of this, there is a great incentive for doctors to not provide the quality of care they could. A patient must defer to the doctor and trust that the doctor is using their knowledge to their best advantage to provide the patient with the best care. Thus, a relationship of trust is established. According to Arrow, the doctor relies on the social obligation of trust to sell their services to the public, even though the patients do not or cannot inspect the quality of a doctor's work. Last, he notes how this unique relationship demands that high levels of education and certification be attained by doctors in order to maintain the quality of medical service provided by doctors. These four ideas from Arrow contributed largely to Akerlof's work.
Spence.
Spence cited no sources for his inspiration. However, he did acknowledge Kenneth Arrow and Thomas Schelling as helpful in discussing ideas during his pursuit of knowledge. He was the first to coin the term "signaling", and encouraged other economists to follow in his footsteps because he believed he had introduced an important concept in economics.
Stiglitz.
Most of Stiglitz's academic inspirations were from his contemporaries. Stiglitz primarily attributes his thinking to articles by Spence, Akerlof, and a few earlier works by him and his co-author Michael Rothschild (Rothschild and Stiglitz 1976), each discussing various aspects of screening and the role of education. Stiglitz's work was a complement to the works of Spence and Akerlof and thus drew from some of the same inspirations from Arrow as Akerlof had.
The discussion of information asymmetry came to the forefront of economics in the 1970s when Akerlof introduced the idea of a "market for lemons" in a paper by the same name (Akerlof 1970). In this paper, Akerlof introduced a fundamental concept that certain sellers of used cars have more knowledge than the buyers, and this can lead to what is known as "adverse selection". This idea may be one of the most important in the history and understanding of asymmetric information in economics.
Spence introduced the idea of "signaling" shortly after the publication of Akerlof's work.
Stiglitz expanded upon the ideas of Spence and Akerlof by introducing an economic function of information asymmetry called "screening". Stiglitz's work in this area referred to the market for insurance, which is rife with information asymmetry problems to be studied.
Impact of 2001 Nobel Work.
These three economists' simple yet revolutionary work birthed a movement in economics that changed how the field viewed the market forever. No longer can perfect information be assumed in some problems, as in most neoclassical models. Information asymmetry began to grow in prevalence in academic literature. In 1996, a Nobel Prize was given to James Mirrlees and William Vickrey for their research back in the 1970s and 1970s on incentive problems when facing uncertainty under asymmetric information. The impact of such academic work can go unrecognized for decades. Differing from the topics presented by Akerlof, Spence and Stiglitz, Mirrlees and Vickrey focused on how income taxation and auctions can be used as a mechanism to draw out information from market participants efficiently. This award marked the importance of information asymmetry in economics. It began a greater discussion on the topic that later led the Nobel committee to award three economists again in 2001 for significant contributions to the aforementioned topics.
These economists continued after the 1970s to contribute to the field of economics and develop their theories, and they have all had significant impacts. Akerlof's work had more impact than just the market for used cars. The pooling effect in the used car market also happens in the employment market for minorities.
One of the most notable impacts of Akerlof's work is its impact on Keynesian theory. Akerlof argues that the Keynesian theory of unemployment being voluntary implies that quits would rise with unemployment. He argues against his critics by drawing upon reasoning based on psychology and sociology rather than pure economics. He supplemented this with an argument that people do not always behave rationally, but rather information asymmetry leads to only "near rationality", which causes people to deviate from optimal behavior regarding employment practices.
Akerlof continues to champion behavioral economics, that these breaches into the fields of psychology and sociology are profound extensions of information asymmetry.
Stiglitz wrote that the trio's work has created a substantial wave in the field of economics. He notes how he explored the economies of third-world countries, and they seemed to exhibit behavior consistent with their theories. He noted how other economists have referred to gaining information as a transaction cost. Stiglitz also attempts to narrow down the sources of information asymmetries. He ties it back to the nature of each individual