micro data heterogeneity and the evaluation of public policy nobel lecture this paper summarizes the contributions of microeconometrics to economic knowledge four main themes are developed 1 microeconometricians developed new tools to respond to econometric problems raised by the analysis of the new sources of micro data produced after the second world war 2 microeconometrics improved on aggregate time series methods by building models that linked economic models for individuals to data on individual behavior 3 an important empirical regularity detected by the field is the diversity and heterogeneity of behavior this heterogeneity has profound consequences for economic theory and for econometric practice 4 microeconometrics has contributed substantially to the scientific evaluation of public policy

macroeconomics after the crisis time to deal with the pretense of knowledge syndrome the recent financial crisis has damaged the reputation of macroeconomics largely for its inability to predict the impending financial and economic crisis to be honest this inability to predict does not concern me much it is almost tautological that severe crises are essentially unpredictable for otherwise they would not cause such a high degree of distress what does concern me about my discipline is that its current core by which i mainly mean the so called dynamic stochastic general equilibrium approach has become so mesmerized with its own internal logic that it has begun to confuse the precision it has achieved about its own world with the precision that it has about the real one this is dangerous for both methodological and policy reasons to be fair to our field an enormous amount of work at the intersection of macroeconomics and corporate finance has been chasing many of the issues that played a central role during the current crisis including liquidity evaporation collateral shortages bubbles crises panics fire sales risk shifting contagion and the like however much of this literature belongs to the periphery of macroeconomics rather than to its core i will discuss the distinction between the core and the periphery of macroeconomics as well as the futile nature of the integrationist movement that is the process of gradually bringing the insights of the periphery into the dynamic stochastic general equilibrium structure i argue that the complexity of macroeconomic interactions limits the knowledge we can ever attain and that we need to place this fact at the center of our analysis we should consider what this complexity does to the actions and reactions of the economic agent and seek analytical tools and macroeconomic policies that are robust to the enormous uncertainty to which we are confined

improving nash by coarse correlation we consider a class of symmetric two person quadratic games where coarse correlated equilibria cce moulin and vial 1978 can strictly improve upon the nash equilibrium payoffs while correlated equilibrium ce aumann 1974 1987 cannot because these games are potential games with concave potential functions we compute the largest feasible total utility in any cce in those games and show that it is achieved by a cce involving only two pure strategy profiles applications include the cournot duopoly and the game of public good provision where the improvement over and above the nash equilibrium payoff can be substantial

consumption insurance between japanese households this paper examines the implication of the full insurance hypothesis and differences in its applicability across groups of households in japan using a rare japanese individual panel data set called the japanese panel survey of consumption the paper first shows that the full insurance hypothesis is strongly rejected for the country as a whole the paper further shows that the rich as well as the poor and also college graduates as well as non college graduates cannot insure their consumption against income shocks in sharp contrast urban residents can pool income shocks completely whereas rural residents cannot rural residents suffer from income risks more seriously than urban residents in japan

complexity and empirical economics this article explores the state of interplay between recent efforts to introduce complex systems methods into economics and the understanding of empirical phenomena the empirical side of economic complexity may be divided into three general branches historical studies the identification of power and scaling laws and analyses of social interactions i argue that while providing useful stylised facts none of these empirical approaches has produced compelling evidence that economic contexts exhibit the substantive microstructure or properties of complex systems this failure reflects inadequate attention to identification problems identification analysis should therefore be at the centre of future work on the empirics of complexity

crime and social interactions the high variance of crime rates across time and space is one of the oldest puzzles in the social sciences this variance appears too high to be explained by changes in the exogenous costs and benefits of crime we present a model where social interactions create enough covariance across individuals to explain the high cross city variance of crime rates this model provides an index of social interactions which suggests that the amount of social interactions is highest in petty crimes moderate in more serious crimes and almost negligible in murder and rape

scaling in economics a reader s guide this paper discusses examples of scaling laws in economics and finance it argues that these regularities in data are useful for disciplining theory formation estimation of the conditional predictive distribution and estimation of impulse response functions is a main goal of econometric work scaling type regularities give useful information on the underlying data generating process the ability of scaling laws to suggest lines of potentially fruitful research was illustrated by the suggestion of several speculative research projects in this paper most importantly the paper stresses the challenges that face empirical and theoretical researchers who wish to make use of scaling law type regularities to improve econometric identification of the underlying causal data generating mechanism copyright 1999 by oxford university press

discrete choice with social interactions this paper provides an analysis of aggregate behavioural outcomes when individual utility exhibits social interaction effects we study generalized logistic models of individual choice which incorporate terms reflecting the desire of individuals to conform to the behaviour of others in an environment of noncooperative decisionmaking laws of large numbers are generated in such environments multiplicity of equilibria in these models which are equivalent to the existence of multiple self consistent means for average choice behaviour will exist when the social interactions exceed a particular threshold local stability of these multiple equilibria is also studied the properties of the noncooperative economy are contrasted with the properties of an economy in which a social planner determines the set of individual choices finally a likelihood function based on the theoretical model is given and conditions for the econometric identifiability of the model are established

technology adoption in the presence of network externalities we analyze technology adoption in industries where network externalities are significant the pattern of adoption depends on whether technologies are sponsored a sponsor is an entity that has property rights to the technology and hence is willing to make investments to promote it key findings include the following 1 compatibility tends to be undersupplied by the market but excessive standardization can occur 2 in the absence of sponsors the technology superior today has a strategic advantage and is likely to dominate the market 3 when one of two rival technologies is sponsored that technology has a strategic advantage and may be adopted even if it is inferior 4 when two competing technologies both are sponsored the technology that will be superior tomorrow has a strategic advantage

zipf s law for cities an explanation zipf s law is a very tight constraint on the class of admissible models of local growth it says that for most countries the size distribution of cities strikingly fits a power law the number of cities with populations greater than s is proportional to 1 s suppose that at least in the upper tail all cities follow some proportional growth process this appears to be verified empirically this automatically leads their distribution to converge to zipf s law

network effects and welfare cultures we empirically examine the role of social networks in welfare participation using data on language spoken at home to better infer networks within an area our empirical strategy asks whether being surrounded by others who speak the same language increases welfare use more for those from high welfare using language groups this methodology allows us to include local area and language group fixed effects and to control for the direct effect of being surrounded by one s language group these controls eliminate many of the problems in previous studies the results strongly confirm the importance of networks in welfare participation

causal parameters and policy analysis in economics a twentieth century retrospective the major contributions of twentieth century econometrics to knowledge were the definition of causal parameters within well defined economic models in which agents are constrained by resources and markets and causes are interrelated the analysis of what is required to recover causal parameters from data the identification problem and clarification of the role of causal parameters in policy evaluation and in forecasting the effects of policies never previously experienced this paper summarizes the development of these ideas by the cowles commission the response to their work by structural econometricians and var econometricians and the response to structural and var econometrics by calibrators advocates of natural and social experiments and by nonparametric econometricians and statisticians this paper considers the definition and identification of causal parameters in economics and their role in econometric policy analysis it assesses different research programs designed to recover causal parameters from data at the beginning of this century economic theory was mainly intuitive and empirical support for it was largely anecdotal at the end of the century economics has a rich array of formal models and a high quality database empirical regularities motivate theory in many areas of economics and data are routinely used to test theory many economic theories have been developed as measurement frameworks to suggest what data should be collected and how they should be interpreted econometric theory was developed to analyze and interpret economic data most econometric theory adapts methods originally developed in statistics the major exception to this rule is the econometric analysis of the identification problem and the companion analyses of structural equations causality and economic policy evaluation although an economist did not invent the phrase correlation does not imply causation 1 economists clari

identification of endogenous social effects the reflection problem this paper examines the reflection problem that arises when a researcher observing the distribution of behaviour in a population tries to infer whether the average behaviour in some group influences the behaviour of the individuals that comprise the group it is found that inference is not possible unless the researcher has prior information specifying the compisition of reference groups if this information is available the prospects for inference depend critically on the population relationship between the variables defining reference groups and those directly affecting outcomes inference is difficult to implossible if these variables are functionally dependent or are statistically independent the prospects are better if the variables defining reference groups and those directly affecting outcomes are moderately related in the population

economic history and the modern economist in this book nine economists and economic historians express their concern for the present state of economics and its development in the future from a variety of different approaches these scholars reassert the importance of economic history in the training of economists and urge that this perspective should not be lost in the future

scaling the volatility of gdp growth rates abstract the distribution of shocks to gdp growth rates is found to be exponential rather than normal their standard deviation scales with gdp where 0 15 0 03 these macroeconomic results place restrictions on the microeconomic structure of interactions between agents

networks or neighborhoods correlations in the use of publicly funded maternity care in california abstract this study focuses on network effects in the utilization of publicly funded prenatal care using vital statistics data from california for 1989 2000 networks are defined using 5 digit zip codes and a woman s racial or ethnic group like others we find evidence that the use of public programs is highly correlated within groups defined using race ethnicity and neighborhoods these correlations persist even when we control for many unobserved characteristics by including zip code year fixed effects and when we focus on the interaction between own group behavior and measures of the potential for contacts with other members of the group contact availability however the richness of our data allows us to go further and to conduct several tests of one important hypothesis about networks that the estimated effects represent information sharing within groups the results cast doubt on the idea that the observed correlations can be interpreted as evidence of information sharing in particular we find estimated effects to be as large or larger among women who have previously used the program as among first time users

sprayed to death path dependence lock in and pest control strategies theoretical literature on the economics of technology has emphasized the effects on technological trajectories of positive feedbacks in a competition among technologies that all perform a similar function the presence of increasing returns to adoptions can force all but one technology from the market furthermore the victor need not be the superior technology this paper provides an empirical study of one technological competition which illuminates this theoretical work it uses theoretical results to explain why chemical control of agricultural pests remains the dominant technology in spite of many claims that it is inferior to its main competitor integrated pest management copyright 1996 by royal economic society

the price dynamics of common trading strategies a deterministic trading strategy can be regarded as a signal processing element that uses external information and past prices as inputs and incorporates them into future prices this paper uses a market maker based method of price formation to study the price dynamics induced by several commonly used financial trading strategies showing how they amplify noise induce structure in prices and cause phenomena such as excess and clustered volatility

direct comparison of agent based models of herding in financial markets abstract the present paper tests a new model comparison methodology by comparing multiple calibrations of three agent based models of financial markets on the daily returns of 24 stock market indices and exchange rate series the models chosen for this empirical application are the herding model of gilli and winker 2003 its asymmetric version by alfarano et al 2005 and the more recent model by franke and westerhoff 2011 which all share a common lineage to the herding model introduced by kirman 1993 in addition standard arch processes are included for each financial series to provide a benchmark for the explanatory power of the models the methodology provides a consistent and statistically significant ranking of the three models more importantly it also reveals that the best performing model franke and westerhoff is generally not distinguishable from an arch type process suggesting their explanatory power on the data is similar

short waves in hungary 1923 and 1946 persistence chaos and lack of control abstract monetary policies follow a complex and chaotic process one that is enhanced when monetary growth is taken to the extreme as in hyperinflation while we have a basic understanding of the complex dynamics of hyperinflation a less explored phenomenon accompanying hyperinflationary episodes is the effect that they have on institutional development building on recent advances in economic history examining monetary policy and institutions this analysis uses more explicit recourse to complexity theory and in particular complex adaptive systems to examine two separate hyperinflationary episodes in hungary 1923 and 1946 delving into the institutional and cultural roots of the inflationary policies of the hungarian government and detailing the institutional effects which succeeded hyperinflation this paper shows that the twin experiences of hungary were both chaotic and created a chaotic and complex aftermath the results of which are still being felt indeed hungary s 1923 and especially its 1946 hyperinflation shows that some economic chaos cannot be restrained by political institutions and in fact the institutions themselves were changed when staring into the abyss hungary also found that the abyss stared back