Mathematical economics

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Mathematical economics refers to the application of mathematical methods to represent economic theories and analyze problems posed in economics. It allows formulation and derivation of key relationships in a theory with clarity, generality, rigor, and simplicity.[1] Mathematics allows economists to form meaningful, testable propositions about wide-ranging and complex subjects which could not be adequately expressed informally. Further, the language of mathematics allows economists to make clear, specific, positive claims about controversial or contentious subjects that would be impossible without mathematics.[2] Much of economic theory is currently presented in terms of mathematical economic models, a set of stylized and simplified mathematical relationships that make clear their assumptions and their implications.

Formal economic modeling began in the late 19th century with the use of differential calculus to describe and predict economic behavior. Economics became more mathematical as a discipline throughout the first half of the 20th century, but it was not until the Second World War that new techniques would allow the use of mathematical formulations in almost all of economics. This rapid systematizing of economics alarmed critics of the discipline as well as some esteemed economists. John Maynard Keynes, Robert Heilbroner, Friedrich Hayek and others have criticized the broad use of mathematical models for human behavior, arguing that some human choices are irreducible to arbitrary quantities or probabilities.

Contents

[edit] History

[edit] Marginalists and the roots of neoclassical economics

Main article: Marginalism
Equilibrium quantities as a solution to two reaction functions in Cournot duopoly.  Each reaction function is expressed as a linear equation dependent upon quantity demanded.
Equilibrium quantities as a solution to two reaction functions in Cournot duopoly. Each reaction function is expressed as a linear equation dependent upon quantity demanded.

The mathematization of economics began in the 19th century. As the physical sciences became more systematized, economists pushed for a quantification in the discipline around the notion of marginal utility. Augustin Cournot and Léon Walras built the tools of the discipline axiomatically around utility, arguing that individuals sought to maximize their utility across choices in a way that could be described mathematically.[3] At the time, it was thought that utility was quantifiable, in units known as utils.[4] The expectation was that advances in statistics would allow formulation of a proper theory of marginal utility. [5] This movement did not succeed in generating a complete mathematical system under which all economic theory would operate, but it did allow for powerful new interpretive tools. In 1918, David Hilbert continued the call for a complete axiomatic system in economics similar to physics and chemistry.[6]

Vilfredo Pareto analyzed microeconomics by treating decisions by economic actors as attempts to change a given allotment of goods to another, more preferred allotment. Sets of allocations could then be treated as Pareto efficient or Pareto optimal when no exchanges could occur between actors that could make at least one individual better off without making any other individual worse off.[7] This frontier of optimal choices between two actors can be shown on the plane as an Edgeworth box while greater numbers of actors requires more dimensions.

[edit] Emergence of modern mathematical economics

The surface of the volatility smile is a 3-D surface whereby the current market implied volatility (Z-axis) for all options on the underlier is plotted against strike price and time to maturity (X & Y-axes).
The surface of the volatility smile is a 3-D surface whereby the current market implied volatility (Z-axis) for all options on the underlier is plotted against strike price and time to maturity (X & Y-axes).[8]

Change across the entire discipline would not come until the end of the Second World War. The exposure of (mostly American and British) economists to engineering problems and problems in large bureaucratic systems would bring about huge changes in the discipline and the nature of university research in general.[9] The War cemented the use of applied mathematics in many disciplines, including economics. Operations research, a newly formed discipline which influenced and was influenced by mathematical economics, would drive much new research and draw considerable government funding over the next few decades. Mathematical economics expanded in scope and use considerably during the immediate post-war period.[10]

In the landmark text Foundations of Economic Analysis (1947), Paul Samuelson identified a common paradigm and mathematical structure across multiple fields in the subject, building on previous work by Alfred Marshall. Foundations took mathematical concepts from chemistry and physics and applied them to economic problems. This broad view (for example, comparing Le Chatelier's principle to tâtonnement) drives the fundamental premise of mathematical economics: systems of economic actors may be modeled and their behavior described much like any other system. This extension followed on the work of the marginalists in the previous century and extended it significantly. Samuelson approached the problems of applying individual utility maximization over aggregate groups with comparative statics, which compares two different equilibrium states after an exogenous change in a variable. This and other methods in the book provided the foundation for mathematical economics in the 20th century.[11][12]

Over the course of the 20th century, articles in "core journals"[13] in economics have been almost exclusively written by economists in academia. As a result, much of the material transmitted in those journals relates to economic theory, and "economic theory itself has been continuously more abstract and mathematical."[14] A subjective assessment of mathematical techniques[15] employed in these core journals showed a decrease in articles that use neither geometric representations nor mathematical notation from 95% in 1982 to 5.3% in 1990.[16]

[edit] Econometrics

Main article: Econometrics

Between the world wars, advances in probability theory resulted in the application of linear regression and time series analysis to economic data, a new method referred to as econometrics. Ragnar Frisch coined the word "econometrics" and helped to found both the Econometric Society in 1930 and the journal Econometrica in 1933.[17][18] Econometrics was originally developed as a tool to validate mathematical theories about economic actors with data from complex sources.[19] While this approach is widespread in the profession today, Richard Lipsey and Chris Achibald at the London School of Economics adopted econometrics to formalize falsifiable statements about mathematical theory. This particular application of econometrics did not produce fruitful results.[20]

Strictly speaking, econometrics refers to empirical interpretation of data while mathematical economics refers to the formulation of models.[21] A study in 2008 of economic articles submitted for publication shows an increasing focus on empirical data and analysis.[22] Some university economics programs cross-list courses in the statistics department and require doctoral students to enroll in supporting courses offered by the statistics department.[23] The Nobel prize has been awarded to econometricians, most recently in 2003 for methods of estimating data with time series volatility and methods in cointegration.[24]

[edit] Application

The IS/LM model is a Keynesian macroeconomic model designed to make predictions about the intersection of "real" economic activity (e.g. spending, income, savings rates) and decisions made in the financial markets (money supply and liquidity preference).  The model is no longer widely taught at the graduate level but is common in undergraduate macroeconomics courses.
The IS/LM model is a Keynesian macroeconomic model designed to make predictions about the intersection of "real" economic activity (e.g. spending, income, savings rates) and decisions made in the financial markets (money supply and liquidity preference). The model is no longer widely taught at the graduate level but is common in undergraduate macroeconomics courses.[25]

Much of classical economics can be presented in simple geometric terms or elementary mathematical notation. Mathematical economics, however, conventionally makes use of calculus and matrix algebra in economic analysis in order to make powerful claims that would be more difficult without these mathematical tools. These are prerequisites for formal study, not only in mathematical economics but in contemporary economic theory generally. Economic problems often involve so many variables that mathematics is the only practical way of attacking and solving them. Alfred Marshall argued that every economic problem which can be quantified, analytically expressed and solved should be treated by means of mathematical work.[26] Economics has become increasingly dependent on mathematical methods and the mathematical tools it employs have become more sophisticated. As a result, mathematics has become considerably more important to professionals in economics and finance. Graduate programs in economics and finance programs in graduate schools of management require strong undergraduate preparation in mathematics for admission and attract an increasingly high number of mathematicians. Applied mathematicians apply mathematical principles to practical problems, such as economic analysis and other economics-related issues, and many economic problems are often defined as integrated into the scope of applied mathematics.[3] This integration results from the formulation of economic problems as stylized models with clear assumptions and falsifiable predictions. This modeling may be informal or prosaic, as it was in Adam Smith's The Wealth of Nations, or it may be formal, rigorous and mathematical.

Broadly speaking, formal economic models are stochastic or non-stochastic and discrete or continuous. At a practical level, quantitative modelling is applied to many areas of economics and several methodologies have evolved more or less independently of each other. [27]

  • Non-stochastic mathematical models may be purely qualitative (for example, models involved in some aspect of social choice theory) or quantitative (involving rationalization of financial variables, for example with hyperbolic coordinates, and/or specific forms of functional relationships between variables). In some cases economic predictions of a model merely assert the direction of movement of economic variables, and so the functional relationships are used only in a qualitative sense: for example, if the price of an item increases, then the demand for that item will decrease. For such models, economists often use two-dimensional graphs instead of functions.
  • Qualitative models are occasionally used. One example is qualitative scenario planning in which possible future events are played out. Another example is non-numerical decision tree analysis. Qualitative models often suffer from lack of precision.

Mathematical economics provides methods to model behavior in diverse, real world situations, including international climate agreements, reactions to changes in divorce laws, and pricing in the futures markets for commodities.[28] [29][30]

[edit] Criticism of mathematical economics

The methods of mathematical economics are widely, though far from exclusively, used in professional publications. While Friedrich Hayek contended that the use of formal techniques projects a scientific exactness that does not appropriately account for informational limitations in the real world, this did not extend to a general critique of mathematical tools in economics.[31] Philosopher Karl Popper offered considerable criticism in the 1940s and 1950s. He argued that the fundamental problem with mathematical economics was that it was tautological. In other words, once economics became a mathematical discipline, it would cease to rely on empirical truth and instead rely on axiomatic proof.[20] Popper asserted that an economic model could either have verifiable assumptions and produce no new information or have unverifiable assumptions and sacrifice formalism for scope.[32] Milton Friedman responded to this by announcing that "all assumptions are unrealistic", charging that economic models should be judged on how well the theory predicts reality, not how well the assumptions accord with reality.[33] Samuelson argued a different tack. He proposed that economic theories should be refutable in principle; if they were refutable in principle, they could not be tautological.[34]

Another criticism of mathematical economics was popularized by Robert Heilbroner in the afterword to his popular book, The Worldly Philosophers. He elaborated on his feelings later in an interview:[35]

I guess the scientific approach began to penetrate and soon dominate the profession in the past twenty to thirty years. This came about in part because of the "invention" of mathematical analysis of various kinds and, indeed, considerable improvements in it. This is the age in which we have not only more data but more sophisticated use of data. So there is a strong feeling that this is a data-laden science and a data-laden undertaking, which, by virtue of the sheer numerics, the sheer equations, and the sheer look of a journal page, bears a certain resemblance to science...That one central activity looks scientific. I understand that. I think that is genuine. It approaches being a universal law. But resembling a science is different from being a science.

Heilbroner addresses one of the core critiques of economics in general here, that "some/much of economics is not naturally quantitative and therefore does not lend itself to mathematical exposition."[36] This critique has been advanced in various forms by economists and other scientists, including Keynes and Paul Joskow. Joskow advanced a particularly harsh critique, observing that a good portion of economic insight came from outside formal models and that those formal, mathematical models were added "ex post" in order to provide a justification for the insight.[37][38]

[edit] Mathematical economists

Famous mathematical economists include, but are not limited to, the following list (by century of birth).

[edit] 19th century

[edit] 20th century

[edit] See also

[edit] Notes

  1. ^ Chiang, Alpha C.; Kevin Wainwright (2005). Fundamental Methods of Mathematical Economics. McGraw-Hill Irwin, 1,2. ISBN 0-07-010910-9. 
  2. ^ Varian, Hal (29-30 October, 1992). "What use is Economic Theory?". Is Economics Becoming a Hard Science?: 1-11. Retrieved on 2008-04-01. 
  3. ^ a b Sheila C., Dow (1999-05-21). "The Use of Mathematics in Economics". ESRC Public Understanding of Mathematics Seminar, Birmingham: Economic and Social Research Council. Retrieved on 2008-07-06. 
  4. ^ While the concept of cardinality has fallen out of favor in neoclassical economics, the differences between cardinal utility and ordinal utility are minor for most applications.
  5. ^ Jevons, W. S. (1871). The Theory of Political Economy, Quoted in Dow, London: Macmillan. 
  6. ^ Hilbert, David (1918). "Axiomatisches Denken". Mathematische Annalen 78: 405-415. Quoted in: David Hilbert and the Axiomatization of Physics (1898-1918). Retrieved on 2008-08-16. 
  7. ^ Nicholson, Walter; Snyder, Christopher (2007). "General Equilibrium and Welfare", Intermediate Microeconomics and Its Applications, 10th, Thompson, 364, 365. ISBN 0324319681. 
  8. ^ Brockhaus, Oliver; Farkas, Michael; Ferraris, Andrew; Long, Douglas; Overhaus, Marcus (2000). Equity Derivatives and Market Risk Models. Risk Books, 13-17. ISBN 9781899332878. Retrieved on 2008-08-17. 
  9. ^ Turner, Fred (2006). From counterculture to cyberculture : Stewart Brand, the Whole Earth Network, and the rise of digital utopianism. Chicago: University Of Chicago Press. ISBN 0226817415. 
  10. ^ Weintraub, E. Roy (2008). "Mathematics and economics". The New Palgrave Dictionary of Economics (2nd Edition). Ed. Durlauf, Steven N.; Blume, Lawrence E.. Macmillan. DOI:10.1057/9780230226203.1063. Retrieved on 2008-07-07. 
  11. ^ Metzler, Lloyd (1948). "Review of Foundations of Economic Analysis". American Economic Review 38 (5): 905-910. ISSN 0002-8282. Retrieved on 2008-05-10. 
  12. ^ Samuelson, Paul ((1947) [1983]). Foundations of Economic Analysis. Harvard University Press. ISBN 0-674-31301-1. 
  13. ^ Liner, Gaines H. (2002). "Core Journals in Economics". Economic Inquiry 40 (1): 140. Oxford University Press. doi:10.1093/ei/40.1.138. Retrieved on 2008-04-10. 
  14. ^ Stigler, George J.; Stigler, Steven J.; Friedland, Claire (April, 1995). "The Journals of Economics". The Journal of Political Economy 103 (2): 339. The University of Chicago Press. ISSN 0022-3808. Retrieved on 2008-08-17. 
  15. ^ Stigler et al. reviewed journal articles in core economic journals (as defined by the authors but meaning generally non-specialist journals) throughout the 20th century. Journal articles which at any point used geometric representation or mathematical notation were noted as using that level of mathematics as its "highest level of mathematical technique". The authors refer to "verbal techniques" as those which conveyed the subject of the piece without notation from geometry, algebra or calculus.
  16. ^ Stigler et al., p. 342
  17. ^ Arrow, Kenneth J. (April, 1960). "The Work of Ragnar Frisch, Econometrician". Econometrica 28 (2): 175, 180. Blackwell Publishing. ISSN 0012-9682. Retrieved on 2008-08-17. 
  18. ^ Bjerkholt, Olav (July, 1995). "Ragnar Frisch, Editor of Econometrica 1933-1954". Econometrica 63 (4): 755. Blackwell Publishing. ISSN 0012-9682. Retrieved on 2008-08-17. 
  19. ^ Lange, Oskar (1945). "The Scope and Method of Economics". Review of Economic Studies 13 (1): 21. The Review of Economic Studies Ltd.. ISSN 0034-6527. Retrieved on 2008-08-17. 
  20. ^ a b Boland, L. A. (2007). "Seven Decades of Economic Methodology", in I. C. Jarvie, K. Milford, D.W. Miller: Karl Popper:A Centenary Assessment. London: Ashgate Publishing, 219. ISBN 9780754653752. Retrieved on 2008-06-10. 
  21. ^ Geweke, John; Horowitz, Joel; Pesaran, Hashem (2008). "Econometrics". The New Palgrave Dictionary of Economics (2nd edition). Ed. Steven N. Durlauf and Lawrence E. Blume. Palgrave Macmillan. DOI:10.1057/9780230226203.0425. Retrieved on 2008-04-22. 
  22. ^ Andrew J., Oswald & Hilda, Ralsmark (2008), "Warwick Economic Research Papers", Some Evidence on the Future of Economics, Warwick Department of Economics, pp. 7, <http://ideas.repec.org/p/wrk/warwec/841.html> 
  23. ^ "Department of Economics". University of Wisconsin.
  24. ^ "2003 Economics Nobel Laureates". Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel. Retrieved on 2008-06-23.
  25. ^ Colander, David C. (2004). "The Strange Persistence of the IS-LM Model". History of Political Economy 36 (Annual Supplement): 305-322. Duke University Press. doi:10.1215/00182702-36-Suppl_1-305. ISSN 0018-2702. Retrieved on 2008-08-18. 
  26. ^ Brems, Hans (Oct., 1975). "Marshall on Mathematics". Journal of Law and Economics 18 (2): 583-585. University of Chicagor Press. ISSN 0022-2186. 
  27. ^ Frigg, R.; Hartman, S. (Feb 27, 2006). in Edward N. Zalta: Models in Science, Stanford Encyclopedia of Philosophy. Stanford, CA: The Metaphysics Research Lab. Retrieved on 2008-08-16. 
  28. ^ McGinty, Matthew (January, 2007). "International Environmental Agreements among Asymmetric Nations". Oxford Economic Papers 59 (1): 45-62. Oxford University Press:. ISSN 0030-7653. Retrieved on 2007-09-04. 
  29. ^ Wolfers, Justin; Stevenson, Betsy (Spring 2007). "Marriage and Divorce: Changes and their Driving Factors". Journal of Economic Perspectives 21 (2): 27-52. American Economic Association. ISSN 0895-3309. Retrieved on 2008-08-16. 
  30. ^ Hamilton, James (April 16, 2008). "Commodity arbitrage". Econbrowser. Retrieved on 2008-08-16.
  31. ^ Hayek, Friedrich (September, 1945). "The Use of Knowledge in Society". American Economic Review 35 (4): 519–530. Retrieved on 2008-04-19. 
  32. ^ Beed, Clive; Kane, Owen (1991). "What Is the Critique of the Mathematization of Economics?". Kyklos 44 (4): 581–612. doi:10.1111/j.1467-6435.1991.tb01798.x. Retrieved on 2008-04-19. 
  33. ^ Friedman, Milton (1953). Essays in Positive Economics. Chicago: University of Chicago Press, 30, 33, 41. ISBN 9780226264035. 
  34. ^ Boland, 220
  35. ^ Heilbroner, Robert (May-June 1999), "The end of the Dismal Science?", Challenge Magazine, <http://findarticles.com/p/articles/mi_m1093/is_3_42/ai_54682627/print> 
  36. ^ Beed & Owen, 584
  37. ^ Joskow, Paul (May, 1975). "Firm Decision-making Policy and Oligopoly Theory". The American Economic Review 65 (2, Papers and Proceedings of the Eighty-seventh Annual Meeting of the American Economic Association): 270–279, Particularly 271. Retrieved on 2008-04-19. 
  38. ^ Keynes, J. M. (September, 1924). "Alfred Marshall 1842-1924". The Economic Journal 34 (135): 333,356. Retrieved on 2008-04-19. 


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