Harold Hotelling | |
---|---|
Born | Fulda, Minnesota, U.S. | September 29, 1895
Died | December 26, 1973 78) | (aged
Alma mater | University of Washington (BA, MA) Princeton University (PhD) |
Known for | Hotelling's T-square distribution Canonical correlation analysis Hotelling's law Hotelling's lemma Hotelling's rule Hotelling's location model Working–Hotelling procedure |
Awards | North Carolina Award 1972 |
Scientific career | |
Fields | Statistics Economics |
Institutions | Univ. of North Carolina 1946–1973 Columbia University 1931–1946 Stanford University 1927–31 |
Doctoral advisor | Oswald Veblen |
Doctoral students | Kenneth Arrow Seymour Geisser Ralph A. Bradley |
Harold Hotelling ( /ˈhoʊtəlɪŋ/ ; September 29, 1895 – December 26, 1973) was an American mathematical statistician and an influential economic theorist, known for Hotelling's law, Hotelling's lemma, and Hotelling's rule in economics, as well as Hotelling's T-squared distribution in statistics. [1] [2] He also developed and named the principal component analysis method widely used in finance, statistics and computer science.
He was associate professor of mathematics at Stanford University from 1927 until 1931, a member of the faculty of Columbia University from 1931 until 1946, and a professor of Mathematical Statistics at the University of North Carolina at Chapel Hill from 1946 until his death. A street in Chapel Hill bears his name. In 1972, he received the North Carolina Award for contributions to science.
Hotelling is known to statisticians because of Hotelling's T-squared distribution which is a generalization of the Student's t-distribution in multivariate setting, and its use in statistical hypothesis testing and confidence regions. He also introduced canonical correlation analysis.
At the beginning of his statistical career Hotelling came under the influence of R.A. Fisher, whose Statistical Methods for Research Workers had "revolutionary importance", according to Hotelling's review. Hotelling was able to maintain professional relations with Fisher, despite the latter's temper tantrums and polemics. Hotelling suggested that Fisher use the English word "cumulants" for Thiele's Danish "semi-invariants". Fisher's emphasis on the sampling distribution of a statistic was extended by Jerzy Neyman and Egon Pearson with greater precision and wider applications, which Hotelling recognized. Hotelling sponsored refugees from European anti-semitism and Nazism, welcoming Henry Mann and Abraham Wald to his research group at Columbia. While at Hotelling's group, Wald developed sequential analysis and statistical decision theory, which Hotelling described as "pragmatism in action".
In the United States, Hotelling is known for his leadership of the statistics profession, in particular for his vision of a statistics department at a university, which convinced many universities to start statistics departments. Hotelling was known for his leadership of departments at Columbia University and the University of North Carolina.
Hotelling has a crucial place in the growth of mathematical economics; several areas of active research were influenced by his economics papers. While at the University of Washington, he was encouraged to switch from pure mathematics toward mathematical economics by the famous mathematician Eric Temple Bell. Later, at Columbia University (where during 1933-34 he taught Milton Friedman statistics) in the '40s, Hotelling in turn encouraged young Kenneth Arrow to switch from mathematics and statistics applied to actuarial studies towards more general applications of mathematics in general economic theory. Hotelling is the eponym of Hotelling's law, Hotelling's lemma, and Hotelling's rule in economics.
Hotelling was influenced by the writing of Henry George and was an editorial adviser for the Georgist journal AJES. [3]
One of Hotelling's most important contributions to economics was his conception of "spatial economics" in his 1929 article. [4] Space was not just a barrier to moving goods around, but rather a field upon which competitors jostled to be nearest to their customers. [5]
Hotelling considers a situation in which there are two sellers at point A and B in a line segment of size l. The buyers are distributed uniformly in this line segment and carry the merchandise to their home at cost c. Let p1 and p2 be the prices charged by A and B, and let the line segment be divided in 3 parts of size a, x+y and b, where x+y is the size of the segment between A and B, a the portion of segment to the left of A and b the portion of segment to the right of B. Therefore, a+x+y+b=l. Since the product being sold is a commodity, the point of indifference to buying is given by p1+cx=p2+cy. Solving for x and y yields:
Let q1 and q2 indicate the quantities sold by A and B. The sellers profit are:
By imposing profit maximization:
Hotelling obtains the economic equilibrium. Hotelling argues this equilibrium is stable even though the sellers may try to establish a price cartel.
Hotelling extrapolates from his findings about spatial economics and links it to not just physical distance, but also similarity in products. He describes how, for example, some factories might make shoes for the poor and others for the rich, but they end up alike. He also quips that, "Methodists and Presbyterian churches are too much alike; cider too homogenous." [4]
As an extension of his research in spatial economics, Hotelling realized that it would be possible and socially optimal to finance investment in public goods through a Georgist land value tax and then provide such goods and services to the public at marginal cost (in many cases for free). This is an early expression of the Henry George theorem that Joseph Stiglitz and others expanded upon. Hotelling pointed out that when local public goods like roads and trains become congested, users create an additional marginal cost of excluding others. Hotelling became an early advocate of Georgist congestion pricing and stated that the purpose of this unique type of toll fee was in no way to recoup investment costs, but was instead a way of changing behavior and compensating those who are excluded. Hotelling describes how human attention is also in limited supply at any given time and place, which produces a rental value; he concludes that billboards could be regulated or taxed on similar grounds as other scarcity rents. Hotelling reasoned that rent and taxation were analogous, the public and private versions of a similar thing. Therefore, the social optimum would be to put taxes directly on rent. [6] Kenneth Arrow described this as market socialism, but Mason Gaffney points out that it is actually Georgism. [7] Hotelling added the following comment about the ethics of Georgist value capture: "The proposition that there is no ethical objection to the confiscation of the site value of land by taxation, if and when the nonlandowning classes can get the power to do so, has been ably defended by [the Georgist] H. G. Brown." [6]
Hotelling made pioneering studies of non-convexity in economics. In economics, non-convexity refers to violations of the convexity assumptions of elementary economics. Basic economics textbooks concentrate on consumers with convex preferences and convex budget sets and on producers with convex production sets; for convex models, the predicted economic behavior is well understood. [8] [9] When convexity assumptions are violated, then many of the good properties of competitive markets need not hold: Thus, non-convexity is associated with market failures, [10] [11] where supply and demand differ or where market equilibria can be inefficient. [8] [11] [12] [13] [14] [15]
In "oligopolies" (markets dominated by a few producers), especially in "monopolies" (markets dominated by one producer), non-convexities remain important. [15] Concerns with large producers exploiting market power initiated the literature on non-convex sets, when Piero Sraffa wrote about firms with increasing returns to scale in 1926, [16] after which Hotelling wrote about marginal cost pricing in 1938. [17] Both Sraffa and Hotelling illuminated the market power of producers without competitors, clearly stimulating a literature on the supply-side of the economy. [18]
When the consumer's preference set is non-convex, then (for some prices) the consumer's demand is not connected. A disconnected demand implies some discontinuous behavior by the consumer as discussed by Hotelling:
If indifference curves for purchases be thought of as possessing a wavy character, convex to the origin in some regions and concave in others, we are forced to the conclusion that it is only the portions convex to the origin that can be regarded as possessing any importance, since the others are essentially unobservable. They can be detected only by the discontinuities that may occur in demand with variation in price-ratios, leading to an abrupt jumping of a point of tangency across a chasm when the straight line is rotated. But, while such discontinuities may reveal the existence of chasms, they can never measure their depth. The concave portions of the indifference curves and their many-dimensional generalizations, if they exist, must forever remain in unmeasurable obscurity. [19] [20]
Following Hotelling's pioneering research on non-convexities in economics, research in economics has recognized non-convexity in new areas of economics. In these areas, non-convexity is associated with market failures, where any equilibrium need not be efficient or where no equilibrium exists because supply and demand differ. [8] [11] [12] [13] [14] [15] Non-convex sets arise also with environmental goods and other externalities, [13] [14] and with market failures, [10] and public economics. [12] [21] Non-convexities occur also with information economics, [22] and with stock markets [15] (and other incomplete markets). [23] [24] Such applications continued to motivate economists to study non-convex sets. [8]
In economics, general equilibrium theory attempts to explain the behavior of supply, demand, and prices in a whole economy with several or many interacting markets, by seeking to prove that the interaction of demand and supply will result in an overall general equilibrium. General equilibrium theory contrasts with the theory of partial equilibrium, which analyzes a specific part of an economy while its other factors are held constant. In general equilibrium, constant influences are considered to be noneconomic, or in other words, considered to be beyond the scope of economic analysis. The noneconomic influences may change given changes in the economic factors however, and therefore the prediction accuracy of an equilibrium model may depend on the independence of the economic factors from noneconomic ones.
Kenneth Joseph Arrow was an American economist, mathematician, writer, and political theorist. Along with John Hicks, he won the Nobel Memorial Prize in Economic Sciences in 1972.
William Jack Baumol was an American economist. He was a professor of economics at New York University, Academic Director of the Berkley Center for Entrepreneurship and Innovation, and Professor Emeritus at Princeton University. He was a prolific author of more than eighty books and several hundred journal articles. He is the namesake of the Baumol effect.
Hirofumi Uzawa was a Japanese economist.
Arnold Carl Harberger is an American economist. His approach to the teaching and practice of economics is to emphasize the use of analytical tools that are directly applicable to real-world issues. His influence on academic economics is reflected in part by the widespread use of the term "Harberger triangle" to refer to the standard graphical depiction of the efficiency cost of distortions of competitive equilibrium.
A Lindahl tax is a form of taxation conceived by Erik Lindahl in which individuals pay for public goods according to their marginal benefits. In other words, they pay according to the amount of satisfaction or utility they derive from the consumption of an additional unit of the public good. Lindahl taxation is designed to maximize efficiency for each individual and provide the optimal level of a public good.
In mathematics, a vector measure is a function defined on a family of sets and taking vector values satisfying certain properties. It is a generalization of the concept of finite measure, which takes nonnegative real values only.
Mathematical economics is the application of mathematical methods to represent theories and analyze problems in economics. Often, these applied methods are beyond simple geometry, and may include differential and integral calculus, difference and differential equations, matrix algebra, mathematical programming, or other computational methods. Proponents of this approach claim that it allows the formulation of theoretical relationships with rigor, generality, and simplicity.
Griffith Conrad Evans was a mathematician working for much of his career at the University of California, Berkeley. He is largely credited with elevating Berkeley's mathematics department to a top-tier research department, having recruited many notable mathematicians in the 1930s and 1940s.
Roy Radner was Leonard N. Stern School Professor of Business at New York University. He was a micro-economic theorist. Radner's research interests included strategic analysis of climate change, bounded rationality, game-theoretic models of corruption, pricing of information goods and statistical theory of data mining. Previously he was a faculty member at the University of California, Berkeley, and a Distinguished Member of Technical Staff at AT&T Bell Laboratories.
Jacques H. Drèze was a Belgian economist noted for his contributions to economic theory, econometrics, and economic policy as well as for his leadership in the economics profession. Drèze was the first President of the European Economic Association in 1986 and was the President of the Econometric Society in 1970.
The Shapley–Folkman lemma is a result in convex geometry that describes the Minkowski addition of sets in a vector space. It is named after mathematicians Lloyd Shapley and Jon Folkman, but was first published by the economist Ross M. Starr.
Roger Guesnerie is an economist born in France in 1943. He is currently the Chaired Professor of Economic Theory and Social Organization of the Collège de France, Director of Studies at the École des hautes études en sciences sociales, and the chairman of the board of directors of the Paris School of Economics.
Ross Marc Starr is an American economist who specializes in microeconomic theory, monetary economics and mathematical economics. He is a professor at the University of California, San Diego.
In economics, non-convexity refers to violations of the convexity assumptions of elementary economics. Basic economics textbooks concentrate on consumers with convex preferences and convex budget sets and on producers with convex production sets; for convex models, the predicted economic behavior is well understood. When convexity assumptions are violated, then many of the good properties of competitive markets need not hold: Thus, non-convexity is associated with market failures, where supply and demand differ or where market equilibria can be inefficient. Non-convex economies are studied with nonsmooth analysis, which is a generalization of convex analysis.
Convexity is a geometric property with a variety of applications in economics. Informally, an economic phenomenon is convex when "intermediates are better than extremes". For example, an economic agent with convex preferences prefers combinations of goods over having a lot of any one sort of good; this represents a kind of diminishing marginal utility of having more of the same good.
Hukukane Nikaido was a Japanese economist.
Charles Frederick Roos was an American economist who made contributions to mathematical economics. He was one of the founders of the Econometric Society together with American economist Irving Fisher and Norwegian economist Ragnar Frisch in 1930. He served as secretary-treasurer during the first year of the society and was elected as president in 1948. He was director of research of the Cowles Commission from September 1934 to January 1937.
Makoto Yano is a Japanese economist, currently the president and chief research officer of the Research Institute of Economy, Trade and Industry. He is also a professor emeritus at Kyoto University and a professor by special appointment at Kyoto University's Institute of Economic Research and Sophia University.
Ferenc Forgó (born 16 April 1942 in Pécs) is a Hungarian economist and mathematician. He is a Doctor of the Hungarian Academy of Sciences and professor emeritus at the Corvinus University of Budapest. His main research interests have been mathematical programming and game theory.
nonconvex OR nonconvexities.
The following have photographs: