a time varying model of rational learning abstract this paper presents an analysis of the stability of the rational expectations equilibrium for a version of the cobweb model under time varying learning it is shown that for appropriate values of a stability parameter the agents can learn how to form rational expectations forecasts using kalman filtering estimation techniques

learning to believe in sunspots a number of authors have shown that competitive economies may possess sunspot equilibria that is rational expectations equilibria in which purely extrinsic uncertainty affects equilibrium prices and allocations 2 such results demonstrate that it does not require a lack of faith in the rationality of market participants to believe that competitive markets may be subject to purely speculative fluctuations driven solely by expectations 3 the mere existence of sunspot equilibria as solutions to a system of marketclearing conditions however might not be judged sufficient to indicate that competitive markets with rational participants could ever be subject to speculative instability the sunspot equilibria represent states of affairs in which agents act differently in the case of different realizations of the sunspot variable and it is rational for each agent to do so but it might be thought unlikely that the beliefs of all the participants in the market could ever come to be coordinated so as to bring about an equilibrium of that kind it is rational to believe that sunspots convey information about future states of affairs once the economy is in a sunspot equilibrium but why would rational agents ever begin to believe in such a thing so as to create the conditions under which the belief is rational in order to address such a question one must go beyond the mere statement of the conditions for equilibrium and discussion of what states of affairs satisfy them one must specify an explicit dynamic process according to which the beliefs of agents adjust when out of equilibrium any exercise of this kind is necessarily unsatisfactory as there is no univocal meaning for the postulate of rational behavior outside of an equilibrium it may well be the case that

beliefs equilibria in an overlapping generations model we consider a standard two generations version of the overlapping generations model agents predict inflation rates on the basis of a perceived law of motion which is estimated by running a linear regression on past inflation rates we introduce the notion of beliefs equilibrium at such an equilibrium i the perceived law of motion is such that it fits the time series of inflation rates best and ii this time series of actual inflation rates is generated when agents use that perceived law of motion we show that beliefs might converge although inflation rates keep on fluctuating these fluctuations are consistent with the limit belief

eductive stability in real business cycle models we reexamine issues of coordination in the standard rbc model is the unique rational expectations equilibrium attainable by rational agents who contemplate the possibility of small deviations from equilibrium surprisingly we nd that coordination cannot be expected even with strong common knowledge assumptions rational agents anticipating small but persistent deviations are led to take actions that eventually contradict the common knowledge assumption this impossibility theorem for eductive learning is not fully overcome when adaptive learning is incorporated into the framework

are policy platforms capitalized into equity prices evidence from the bush gore 2000 presidential election abstract this paper tests for the capitalization of policy platforms into equity prices using a sample of 70 firms favored under bush or gore platforms during the 2000 u s presidential election two sources of daily data during the six months leading up to the election are incorporated firm specific equity returns and the probability of a bush victory as implied by prices from the iowa electronic market for this group of politically sensitive firms the daily baseline estimates demonstrate that platforms are capitalized into equity prices under a bush administration relative to a counterfactual gore administration bush favored firms are worth 3 more and gore favored firms are worth 6 less implying a statistically significant differential return of 9 estimates based on weekly returns are even stronger suggesting a differential return of 16 the most sensitive sectors include tobacco worth 13 more under a favorable bush administration microsoft competitors worth 15 less under an unfavorable bush administration and alternative energy companies worth 16 less under an unfavorable bush administration a corresponding analysis of campaign contributions which allows for heterogeneity in the importance of policy platforms to the firms supports the baseline estimates

oligopoly game price makers meet price takers abstract the paper studies an oligopoly game where firms can choose between price taking and price making strategies on a mixed market price takers are always better off than price makers though the profits of both types decline in the number of price takers we investigate and confront two possibilities of firms decisions about their types forward looking equilibrium reasoning and backward looking individual learning we find that the cournot outcome is the only equilibrium prediction and it is learnable if firms are sufficiently sensitive to profit differences however with a larger number of firms a unilateral deviation from cournot behavior becomes profitable under learning this incentive creates a space for permanent oscillations over different markets with a positive but low number of price takers

learning in expectation formation with applications to cattle and beef exports the paper briefly considers problems associated with rational expectations and formulates a more general model which allows for situations where economic agents do not immediately arrive at a fully rational solution it incorporates a learning mechanism whereby agents can provisionally adopt hypothetically derived expectations as a basis for comparison with the actual outturns utilizing the resultant past expectational errors as indicators of the likelihood of prospective future outcomes agents make explicit allowance a rational solution thus in situations where complete information is not freely available rationality would be approximated over time by means of a dynamic learning process which is founded on a firm empirical approach this essential empiricism requires that the problem be examined on the basis of direct observation of applied situations therefore the method is implemented and analysed with reference to irish foreign trade in fat cattle carcase and processed beef simultaneous equati

stable near rational sunspot equilibria abstract we introduce a new class of solutions to nonlinear forward looking models called near rational sunspot equilibria nrse nrse are natural nonlinear extensions of the usual sunspot equilibria associated with the linearized version of the economy and are near rational in that agents use the optimal linear forecasting model when forming expectations generic results for existence and stability under learning are established nrse in indeterminate nonlinear models are found to be stable under learning provided that the corresponding linearized model s minimal state variable solution is e stable nrse are readily computable and our results make it possible to use the standard linear tools to search for stable nrse we illustrate our results using a canonical nonlinear new keynesian model

heterogeneous expectations adaptive learning and evolutionary dynamics this paper presents a linear self referential macroeconomic model with the possibility of multiple equilibria where agents have the choice of using one of two forecasting models one of minimum state variable form and the other of sunspot form to form expectations of current and future prices endogenous predictor selection is modeled as an evolutionary game where individuals choose among the forecasting models based on relative performance some nash solutions are not relevant as they are not stable under evolutionary or adaptive learning finally it is shown that the sunspot equilibrium is fragile against temporary shocks to information costs

equilibrium selection observability and backward stable solutions abstract the robustness of stability under learning to observability of exogenous shocks is examined regardless of observability assumptions the minimal state variable solution is robustly stable under learning provided the expectational feedback is not both positive and large while the nonfundamental solution is never robustly stable overlapping generations and new keynesian models are considered and concerns raised in cochrane 2011 2017 are addressed

reading cournot reading nash the creation and stabilisation of the nash equilibrium the concept of the cournot nash equilibrium is central to noncooperative game theory and the latter s use in macroeconomic theory this paper considers the creation of this theoretical construct examining the separate contributions of both cournot and nash and showing how the two were ultimately joined together in the eyes of contemporary economic theorists rather than simply showing how cournot served as a precursor to nash the author challenges the traditional approach and emphasizes the shifts in interpretation of their respective contributions in so doing he addresses some pertinent questions about the manner in which economic theorists view the evolution of their own discipline copyright 1994 by royal economic society

introduction to the stability of rational expectations equilibrium abstract this paper surveys the literature which examines the stability of the expectations that agents are assumed to have in a rational expectations equilibrium ree this issue is more complex than the usual statistical estimation problem because the relationship between observable variables and payoff relevant variables is endogenous one approach taken in the literature yields convergence to a ree but requires agents to have extensive knowledge about the structure and dynamics of the model that prevails while they learn a second approach does not assume that agents have correctly specified likelihood functions and finds that ree may not be stable

expectation shocks and learning as drivers of the business cycle psychological factors market sentiments and less than fully rational shifts in beliefs are widely believed to play a role in the economy yet they are rarely considered in macroeconomic models this paper evaluates the empirical role of expectational shocks on business cycle fluctuations the paper relaxes the rational expectations assumption to exploit survey data on expectations in the estimation of a new keynesian model which allows for learning by economic agents expectation shocks affect the formation of expectations and capture waves of optimism and pessimism that lead agents to form forecasts that deviate from those implied by their learning model the empirical results uncover a crucial role for these novel expectations shocks as a major driving force of the u s business cycle expectation shocks regarding future real activity are the main source of economic fluctuations accounting for roughly half of business cycle fluctuations

expectations and the stability problem for optimal monetary policies eine auf den fundamentaldaten beruhende regelbindung der geldpolitik ohne selbstverpflichtung die bei vollkommen rationalen erwartungen der privaten akteure optimal ware ist instabil wenn diese akteure de facto den ublichen regeln des adaptiven lernens folgen dieses problem lasst sich dadurch beheben dass die erwartungen privater akteure berucksichtigt und in geeigneter weise in die optimale geldpolitik einbezogen werden diese eindeutige schlusfolgerung gilt auch dann wenn sich der geldpolitische entscheidungstrager und die privaten akteure in einem simultanen lernprozess befinden unsere ergebnisse zeigen wie wichtig es ist die geldpolitik angemessen zu gestalten und dabei nicht nur die fundamentaldaten sondern auch direkt die beobachteten erwartungen privater haushalte und unternehmen zu berucksichtigen

equilibrium in strategic interaction the contributions of john c harsanyi john f nash and reinhard selten during the past 15 years or so a game theoretic revolution of economics has taken place microeconomic theory has been rewritten in the language of a game theory see kreps 1 990b i publications in industrial organization differ substantially from work published in this area two decades ago in macroeconomics issues of time consistency credibility and reputation have been analyzed by means of game theoretic tools trade theory has been cast in game theoretic terms in financial economics problems of market micro structure are analyzed by means of non cooperative games fundamental concepts and techniques developed by this year s nobel laureates have enabled this revolution to take place as kreps writes

ordinary least squares learning and nonlinearities in macroeconomics the paper reviews the literature on adaptive learning in macroeconomic settings where the formation of expectations is particularly relevant special attention will be given to simple two period overlapping generations models with a unique fixed point perfect foresight equilibrium in this kind of scenario eventual long term periodic and a periodic cycles are exclusively the result of the process of learning the outcome that high rates of money growth have a potentially destabilizing effect generating periodic fluctuations and chaos is emphasized the persistence of systematic forecast errors in a scenario where agents are supposed to act rationally is relevant in this context and it will be thoroughly discussed resorting to the notions of self fulfilling mistakes consistent expectations equilibria and beliefs equilibria

three little known and yet still significant contributions of lloyd shapley abstract this paper makes three corrections in the literature by restating three little known and yet still significant contributions of lloyd shapley 1 shapley 1955 not gillies 1953 gillies 1959 first defined the core solution 2 shapley 1956 first defined and studied the noncooperative solution in multiobjective games and 3 shapley 1987 revealed a fundamental error in existing noncooperative game theory

local convergence properties of a cobweb model with rationally heterogeneous expectations abstract this paper gives local stability conditions for convergence of the price dynamics in a cobweb model with rationally heterogeneous expectations generalizing the example of brock and hommes 1997 when agents choose between rational naive and adaptive beliefs the steady state may be locally asymptotically stable if the adaptive predictor places enough weight on past prices and is costless if adaptive expectations are sufficiently more costly than naive expectations the steady state will be an unstable saddle point our results imply that adding a choice can stabilize a system which is unstable under the brock and hommes model these results illustrate how the critical parameter that governs stability is dependent on the array of available predictors

intrinsic heterogeneity in expectation formation we introduce the concept of misspecification equilibrium to dynamic macroeconomics agents choose between a list of misspecified econometric models and base their selection on relative forecast performance a misspecification equilibrium is a stochastic process in which agents forecast optimally given their choices with forecast model parameters and predictor proportions endogenously determined under appropriate conditions the misspecification equilibrium will exhibit intrinsic heterogeneity in which all predictors are used at all times even in the neoclassical limit in which only the most successful predictors are used this equilibrium is attainable under least squares learning and dynamic predictor selection based on average profits

e stability vis a vis determinacy in regime switching models abstract this paper examines e stability determinacy and indeterminacy in a general class of regime switching models with lagged endogenous variables using determinacy conditions from cho 2016 2020 our first result extends mccallum 2007 to models with time varying parameters the unique mean square stable equilibrium is e stable if agents have current information and one period ahead decision rules further we address the existence of e stable non fundamental equilibria and find that iteratively e stable equilibria of indeterminate switching models can exist finally we show that indeterminate new keynesian models with persistent recurring interest rate peg regimes admit iteratively e stable equilibria in special cases the iterative e stability condition coincides with the long run taylor principle

adjustment costs learning and indeterminacy abstract i compare the adjustment cost and learning approaches to resolving indeterminacy of perfect foresight equilibrium in a continuous time model with local indeterminacy rapid learning tends to select different perfect foresight equilibria of the original model than does the inclusion of vanishing adjustment costs this difference has implications for the dynamic response of the economy to unanticipated shocks

learning about monetary policy rules abstract we study macroeconomic systems with forward looking private sector agents and a monetary authority that is trying to control the economy through the use of a linear policy feedback rule we use stability under recursive learning a la evans and honkapohja learning and expectations in macroeconomics princeton university press princeton new jersey 2001 as a criterion for evaluating monetary policy rules in this context we find that considering learning can alter the evaluation of alternative policy rules

nash equilibrium and the history of economic theory john nash s formulation of noncooperative game theory was one of the great breakthroughs in the history of social science nash s work in this area is reviewed in its historical context to better understand how the fundamental ideas of noncooperative game theory were developed and how they changed the course of economic theory

liquidity traps and expectation dynamics fiscal stimulus or fiscal austerity we examine global dynamics under infinite horizon learning in new keynesian models where the interest rate rule is subject to the zero lower bound as in evans guse and honkapohja 2008 the intended steady state is locally but not globally stable unstable deflationary paths emerge after large pessimistic shocks to expectations for large expectation shocks that push interest rates to the zero bound a temporary fiscal stimulus or a policy of fiscal austerity appropriately tailored in magnitude and duration will insulate the economy from deflation traps however fiscal switching rules that automatically kick in without discretionary fine tuning can be equally effective

adaptive learning and monetary exchange abstract this paper investigates three classic questions in monetary theory how can an intrinsically worthless asset such as fiat money maintain value as a medium of exchange what are the short run and long run effects of a change in the money supply what is the social cost of inflation i answer these questions using a microfounded model of monetary exchange that replaces the rational expectations assumption with an adaptive learning rule first i show that monetary exchange is a robust arrangement in the sense that agents are able to learn the stationary monetary equilibrium while the non monetary equilibrium is unstable under learning second an unanticipated monetary injection has real effects in the short run because learning the value of money takes time in the long run agents successfully learn the value of money hence money is neutral third under a constant money growth policy an increase in the growth rate of money increases output in the short run producing a short run phillips curve a ten percent increase in the money growth rate has a social cost of 0 41 percent of output per year alternatively a ten percent decrease in the money growth rate has a social benefit of 0 37 percent of output per year

money as a medium of exchange in an economy with artificially intelligent agents abstract we study the exchange economies of kiyotaki and wright 1989 in which agents must use a commodity or fiat money as a medium of exchange if trade is to occur our agents are artificially intelligent and are modeled as using classifier systems to make decisions in the assignment of credit within the classifier systems we introduce some innovations designed to study sequential decision problems in a multi agent environment for most economies that we have simulated trading and consumption patterns converge to a stationary nash equilibrium even if agents start with random rules in economies with multiple equilibria the only equilibrium that emerges in our simulations is the one in which goods with low storage costs play the role of medium of exchange i e the fundamental equilibrium of kiyotaki and wright

macroeconomics and a bit more reality macroeconomics in its widest sense is a topic which is too diverse to be usefully discussed in a single article i will therefore take a very narrow view of what might be included under this general title and focus my attention on my own main area of interest the development and use of large macro econometric models this is an area which has a long tradition and literature stemming form the pioneering work of tinbergen i937 and the cowles commission klein i950 an extensive survey of the development of modelling may be found in bodkin klein and marwah i99i macroeconometric modelling grew rapidly in importance during the late i950s and the i960s going on to achieve a very influential role inmacroeconomic policy making during the i970s its failure to deliver the detailed economic control which it had seemed to promise then led to a barrage of attacks ranging from disillusion and sceptiscism on the part of policy makers to detailed and well argued acadeinic criticism of the basic methodology of the approach perhaps the most powerful and influential of these academic arguments came from sims i980 in his article macroeconomics and reality sims argued on three quite separate grounds against the basic process of model identification which lies at the heart of the cowles commission methodology firstly that economic theory gives rise to identification restrictions which are typically more complex than those traditionally applied in macroeconometric models in particular he said that theory normally implies complex cross equation restrictions which require system estimation and which cannot be imposed on a single equation basis secondly that traditional identification conditions are often met simply because of the presence of dynamics in the models sims argued that this identification is spurious and technically invalid as purely dynamic terms cannot help in structural identification in the conventional sense finally he said that the importance of expectations effects and the interaction of policy regimes and agents expectations make identification very difficult sims argued that any one of these problems would form a challenging but feasible research agenda but that doing all of these at once would be a programme which is so challenging as to be impossible in the short run he then proposed a methodology based on vector auto regressive var models

examining political connections to study institutional change evidence from two unexpected election outcomes in south korea we argue that the analysis of multiple political connections in an event study framework can improve the study of institutional change based on a unique data set of multiple political relationships of 4 936 south korean board of director members we show that the large business conglomerates the chaebol did not benefit from the unexpected conservative election victories in the 2012 south korean parliamentary and presidential elections personal connections to the presidential candidates and to the opposition party were relevant for the stock returns of small firms our findings suggest that korea s political economy has evolved into a hybrid regime in which the political power of large multinational corporations is limited but political connections still matter for smaller firms the corruption scandal that led to the impeachment of president park in 2017 and the long term development of market capitalisation appear to be congruent with the results of our study

inflation determination with taylor rules is new keynesian analysis critically flawed abstract cochrane 2007 has strongly questioned the basic economic logic of current monetary policy analysis arguing that new keynesian nk models imply rational expectations paths with explosive inflation that do not imply explosions in real variables relevant for transversality conditions consequently the usual logic does not rule out solutions with explosive inflation that result does not however justify negative conclusions about nk analysis for a different criterion is logically satisfactory it is that to be plausible a re solution must satisfy the property of least squares learnability adoption of this criterion serves to justify in principle the bulk of current mainstream analysis

liquidity traps learning and stagnation we examine global economic dynamics under learning in a new keynesian model in which the interest rate rule is subject to the zero lower bound under normal monetary and fiscal policy the intended steady state is locally but not globally stable large pessimistic shocks to expectations can lead to deflationary spirals with falling prices and falling output to avoid this outcome we recommend augmenting normal policies with aggressive monetary and fiscal policy that guarantee a lower bound on inflation in contrast policies geared toward ensuring an output lower bound are insufficient for avoiding deflationary spirals

effects of financial liberalisation and political connection on listed chinese firms financing constraints this paper examines the impact of recent financial liberalization in china on the financing constraints of publicly listed chinese firms with and without politically connected ceo chairman two continuous indices are used to measure the evolution and intensity of financial reforms a financial liberalization index and a capital control index the results indicate that while firms without politically connected ceo chairman face significant financing constraints and politically connected firms do not financial liberalization has reduced the constraints for the former similarly lower capital control in china s equity market lessens credit constraints for non connected firms no statistically significant impact is detected with regards to firms that have ceo chairman with powerful political background

least squares learning and the stability of equilibria with externalities this paper studies the stability of competitive equilibria in a model of aggregate employment when the representative agent uses a least squares forecasting procedure it is shown that the pareto inferior low employment steady state is always unstable under least squares learning even if it is stable under perfect foresight the high employment steady state is stable under learning if and only if it is saddle point stable under perfect foresight this weakens multiple equilibrium theories of coordination failure that purport to explain persistently high unemployment the pareto superior high employment steady state will be the focal point of individual forecasting

the jeffords effect abstract in may 2001 senator james jeffords left the republican party and tipped control of the u s senate to the democrats this paper uses the surprise event to demonstrate what i term the jeffords effect changes in the political landscape have large effects on the market value of firms i use a firm s soft money donations to the national parties as the measure of how the firm aligns itself politically in this event study a firm lost 8 percent of market capitalization the week of jeffords s switch for every 250 000 it gave to the republicans in the previous election cycle on the basis of the point estimates the stock price gain associated with democratic donations is smaller than the loss associated with republican donations but the estimates are consistent with the effects being equal and opposite the results withstand several robustness checks and the effects appear to persist over time

when do institutions bite historical institutionalism and the politics of institutional change historical institutionalist theories of endogenous change have enhanced our understanding of institutional development by providing a theoretical vocabulary for analyzing how institutions may be renegotiated over the long run by social and political actors in these theories however the causal impact of institutions themselves on political outcomes including their own change and reform is less developed a significant problem for an institutional research program this paper addresses this problem by proposing strategies that integrate historical institutionalism s insights into endogenous institutional change with a systematic analysis of the institutional conditions under which bottom up processes of gradual change are likely to be counteracted in particular the institutionalization of cultural categories and the allocation of power over the timing of reform within institutional and policy configurations are important variables for understanding how pre existing institutions may enable institutional incumbents to channel delay or prevent institutional change

the globalization of liberalization policy diffusion in the international political economy one of the most important developments over the past three decades has been the spread of liberal economic ideas and policies throughout the world these policies have affected the lives of millions of people yet our most sophisticated political economy models do not adequately capture influences on these policy choices evidence suggests that the adoption of liberal economic practices is highly clustered both temporally and spatially we hypothesize that this clustering might be due to processes of policy diffusion we think of diffusion as resulting from one of two broad sets of forces one in which mounting adoptions of a policy alter the benefits of adopting for others and another in which adoptions provide policy relevant information about the benefits of adopting we develop arguments within these broad classes of mechanisms construct appropriate measures of the relevant concepts and test their effects on liberalization and restriction of the current account the capital account and the exchange rate regime our findings suggest that domestic models of foreign economic policy making are insufficient the evidence shows that policy transitions are influenced by international economic competition as well as the policies of a country s sociocultural peers we interpret the latter influence as a form of channeled learning reflecting governments search for appropriate models for economic policy

oligopoly games and the cournot bertrand model a survey traditional oligopoly models hold that firms compete in the same strategic variable output cournot or price bertrand alternatively a hybrid model allows some firms to compete in output and other firms to compete in price also known as the cournot bertrand model when the choice of strategic variable is endogenous the established dominant strategy is output competition a growing body of work demonstrates however that the cournot bertrand outcome can be a subgame perfect nash equilibrium in the presence of market asymmetries observations of real world markets consistent with cournot bertrand behavior bolster justification for the model and have stimulated an impressive and evolving literature on advances and applications we lay out the roots of the cournot bertrand model and explore a number of model developments we categorize 12 primary models in the literature based on alternative assumptions in particular some authors consider when the timing of play as well as the choice of strategic variable are endogenous altogether this research identifies when cournot bertrand behavior can emerge in a dynamic setting and under alternative market conditions we also review the cournot bertrand model applications in the fields of international economics industrial organization labor and public economics we expect the literature to continue to expand in the future

do lenders favor politically connected firms rent provision in an emerging financial market corruption by the politically connected is often blamed for economic ills particularly in less developed economies using a loan level data set of more than 90 000 rms that represents the universe of corporate lending in pakistan between 1996 and 2002 we investigate rents to politically connected rms in banking classifying a rm as political if its director participates in an election we examine the extent nature and economic costs of political rent provision we nd that political rms borrow 45 percent more and have 50 percent higher default rates such preferential treatment occurs exclusively in government banks private banks provide no

the perils of taylor rules abstract since john taylor s 1993 carnegie rochester conf ser publ policy39 195 214 seminal paper a large literature has argued that active interest rate feedback rules that is rules that respond to increases in inflation with a more than one for one increase in the nominal interest rate are stabilizing in this paper we argue that once the zero bound on nominal interest rates is taken into account active interest rate feedback rules can easily lead to unexpected consequences specifically we show that even if the steady state at which monetary policy is active is locally the unique equilibrium typically there exist an infinite number of equilibrium trajectories originating arbitrarily close to that steady state that converge to a liquidity trap that is a steady state in which the nominal interest rate is near zero and inflation is possibly negative journal of economic literature classification numbers e52 e31 e63

interest rate control and nonconvergence to rational expectations this paper investigates the feasibility of a monetary policy aimed at pegging the nominal rate of interest it shows that under general conditions such a policy would produce the well known cumulative process despite the fact that there exists a well behaved rational expectations equilibrium with no tendency for inflation to accelerate or decelerate the cumulative process shows up as the failure of learning to converge to rational expectations specifically the paper shows first in a conventional is lm model with an expectations augmented phillips curve and then in a micro based finance constraint model that if people follow any learning rule based on experience that satisfies a weak condition then the sequence of temporary equilibria under a policy of interest pegging cannot converge the nonconvergent path that will be observed accords with the familiar cumulative process in that inflation accelerates if the market rate of interest has been pegged below the natural rate

adaptive behavior and economic theory the relationship between psychological and economic views of behavior once a subject of heavy dispute is now understood in a very similar way by practitioners of both these disciplines and of our sister social sciences in general terms we view or model an individual as a collection of decision rules rules that dictate the action to be taken in given situations and a set of preferences used to evaluate the outcomes arising from particular situation action combinations these decision rules are continuously under review and revision new decision rules are tried and tested against experience and rules that produce desirable outcomes supplant those that do not i use the term adaptive to refer to this trial anderror process through which our modes of behavior are determined if one is interested in modeling particular decisions in any very explicit way it is obviously necessary to think about rather narrow aspects of an individual s entire set of decision rules his or her personality experimental psychology has traditionally focused on the adaptive process by which decision rules are replaced by others in this tradition the influence of the subject s or as an economist says the agent s preferences this essay uses a series of examples to illustrate the use of rationality and adaptation in economic theory it is argued that these hypotheses are complementary and that stability theories based on adaptive behavior may help to narrow the class of empirically interesting equilibria in certain economic models an experiment is proposed to test this idea

inferring changes in expectation behavior over time an application of nonlinear time varying parameters estimation this article develops a new method for inferring the structure of agents expectations from macroeconomic time series two versions of a somewhat stylized macroeconomic model are examined expectations of money growth are a central driving variable assumed to be formed as a time varying weighted average of alternative money growth models the weights are estimated as time varying parameters jointly with the structural parameters for the model using a nonlinear time varying parameters method developed for the article the results allow us to infer how agents may have revised their beliefs about competing money growth models including federal open market committee announcements over the sample

learning with misspecification in an artificial currency market abstract agents evolve their forecast rules over time via a modified genetic algorithm in a simple artificial currency market these forecast rules can be nonlinearly misspecified when the misspecification is suppressed learning tends to be complete when it is not suppressed learning can generate persistent exchange rate dynamics

learning and model validation this paper studies adaptive learning with multiple models an agent operating in a self referential environment is aware of potential model misspecification and tries to detect it in real time using an econometric specification test if the current model passes the test it is used to construct an optimal policy if it fails the test a new model is selected as the rate of coefficient updating decreases one model becomes dominant and is used almost always dominant models can be characterized using the tools of large deviations theory the analysis is used to address two questions posed by sargent s phillips curve model

a simple recursive forecasting model abstract we compare the performance of alternative recursive forecasting models a simple constant gain algorithm used widely in the learning literature both forecasts well out of sample and also provides the best fit to the survey of professional forecasters

social learning and monetary policy rules we analyse the effects of social learning in a monetary policy context social learning might be viewed as more descriptive of actual learning behaviour in complex market economies in our model taylor principle governs uniqueness and expectational stability of rational expectations equilibrium ree under homogeneous recursive algorithms we find that the taylor principle is not necessary for convergence to ree minimum state variable msv equilibrium under social learning sunspot equilibria exist in the indeterminate region our agents cannot co ordinate on a sunspot equilibrium in general form specification however they can co ordinate on common factor specification we contribute to the use of genetic algorithm learning in stochastic environments

political connection bank credits and growth evidence from turkey the pervasive existence of government owned banks in emerging economies is often justified by their provision of access to credit in remote and underdeveloped regions that are ignored by private banks this paper analyses whether credits provided by government owned and private banks have a significant role in regional growth and whether this role changes in politically connected areas in turkey our findings imply that private banks significantly improve the economic well being in all turkish provinces regardless of their development level or their political connection with the ruling party however credits by government owned banks are found to be positively related to the per capita growth rate only in the less developed provinces that are advocates of the ruling political party and also developed but not politically connected provinces these results suggest that government owned bank credits as implied by the political view are used for funding politically desirable projects or politically connected borrowers

learning to live in a liquidity trap abstract the taylor rule in combination with the zero lower bound on nominal rates has been shown to create an unintended liquidity trap equilibrium the relevance of this equilibrium has been challenged on the basis that it is not stable under least square learning in this paper we show that the liquidity trap equilibrium is stable under social learning the learning mechanism we employ includes three realistic elements mutation crossover and tournaments we show that agents can learn to have pessimistic sentiments about the central bank s ability to generate price growth giving rise to a stochastically stable environment characterized by deflation and stagnation this article is part of a special issue entitled fiscal and monetary policies

elections and political risk new evidence from the 2008 taiwanese presidential election abstract we examine the effects of party platforms on the economic opportunities of firms using a unique data set from a political prediction market in taiwan a country with two dominant parties whose political cleavage derives mainly from a single issue the one china principle we find that during the 2008 presidential campaign the share price of taiwanese firms with investments in the mainland responded strongly and positively to a positive electoral outlook for the kmt the party which advocates lifting caps on cross strait investment in mainland china the response is strongest for those firms who have already hit their caps

games economists play a noncooperative view for some thirty years following world war ii most bright young economists did not go into industrial organization it was not hard to see why this was so the quick big payoffs in economics tend to go to theorists and industrial organization was a subject in which theory was not only unsatisfactory but moribund the promise of the chamberlin robinson revolution of the early 1930s had not been fulfilled and while institutional and verbaltheoretic writings on the subject were sometimes illuminating there was no hard analytic theory formalizing the structure conduct performance paradigm oligopoly in particular showed no signs of analytic tractability today the atmosphere is altogether different the profession is full of young theorists whose principal occupation is industrial organization indeed industrial organization has become the hot topic for microtheorists journals meetings and seminars abound in research on oligopoly and judging by the market this is a booming industry of course the principal reason for the change is the rise of game theory and its applications in these areas von neumann and morgenstern s great work was published in 1944 and hailed immediately by theorists von neumann and morgenstern 1944 jacob marschak indeed stated in reviewing it marschak 1946 p 1 15 ten more such books and the progress of economics is assured nevertheless it was not until the last decade that game theory came to the ascendant as the premier fashionable tool of microtheorists that ascendancy appears fairly complete bright young theorists today tend to think of every problem in game theoretic terms including problems that are easier to deal with in other forms every department feels it needs at least one game theorist or at least one theorist who thinks in game theoretic terms oligopoly theory in particular is totally dominated by the game theoretic approach the field appears to be in an exciting stage of ferment to understand why i believe that such excitement is not warranted it is necessary to step back briefly review the history of oligopoly theory before the game theory revolution and consider what it is that one wants theory to deliver

politicians and banks political influences on government owned banks in emerging markets abstract government ownership of banks is very common in countries other than the united states this paper provides cross country bank level empirical evidence about political influences on these banks it shows that government owned banks increase their lending in election years relative to private banks this effect is robust to controlling for country specific macroeconomic and institutional factors as well as bank specific factors the increase in lending is about 11 of a government owned bank s total loan portfolio or about 0 5 of the median country s gdp per election per government owned bank

event studies in economics and finance the event study is an important research tool in economics and finance the goal of an event study is to measure the effects of an economic event on the value of firms event study methods exploit the fact that given rationality in the marketplace the effects of an event will be reflected immediately in security prices thus the impact can be measured by examining security prices surrounding the event in this paper event study methods are described including some of the potential complications an example is included to illustrate the approach

expectational diversity in monetary economies abstract we investigate an overlapping generations monetary economy in which expectations depend upon backward looking predictors of the future price level we use discrete choice theory to model how agents select a predictor based on its past forecast error letting the number of available predictors tend to infinity we obtain the large type limit of the system taking the large type limit dramatically reduces the number of free parameters while maintaining the expectational diversity which we argue is necessary for constructing plausible learning based models the model s dynamics are strongly influenced by the intensity of choice which measures how sensitive an agent s predictor choice is to differences in forecast errors across predictors when the intensity of choice is low the monetary steady state is stable as the intensity of choice increases and if certain parametric restrictions are met the system undergoes a hopf bifurcation in which case we document the existence of highly irregular equilibrium price paths