comparing the post earnings announcement drift for surprises calculated from analyst and time series forecasts post earnings announcement drift is the tendency for a stock s cumulative abnormal returns to drift in the direction of an earnings surprise for several weeks following an earnings announcement we show that the drift is significantly larger when defining the earnings surprise using analysts forecasts and actual earnings from i b e s than when using a time series model based on compustat earnings data neither compustat s policy of restating earnings nor the inclusion of special items in reported earnings contribute significantly to the disparity in drift magnitudes rather our results suggest that this disparity is attributable to differences between analyst forecasts and those of time series models or at least to factors correlated with these differences further we document that analyst forecasts lead to return patterns around future earnings announcements that differ from those observed when using time series models suggesting that the two types of surprises may capture somewhat different forms of mispricing

social networks and the dynamics of labour market outcomes evidence from refugees resettled in the u s recent theoretical work suggests that social networks may play an important role in the dynamics of employment and wages across groups of individuals this paper provides empirical evidence of job information flows within social networks and the non linear relationship between social network size and labor market outcomes an extended version of the model developed by calvo armengol and jackson 2004 shows that competition can exist between network members for job referrals and investigates the dynamics between the size of a social network the tenure of network members and labor market outcomes the predictions of the model are tested empirically using a unique data set of refugees resettled in the u s from 2001 2005 the empirical strategy exploits the special institutional environment of refugee resettlement i find that a one standard deviation increase in the number of network members who have arrived in the u s one year ago lowers the probability of employment by 4 9 and the average hourly wage by 70 conversely as predicted by the model more tenured network members improve labor market outcomes for recently arrived refugees

integrating behavioral choice into epidemiological models of aids increased hiv risk creates incentives for people with low sexual activity to reduce their activity but may make high activity people fatalistic leading them to reduce their activity only slightly or actually increase it if high activity people reduce their activity by a smaller proportion than low activity people the composition of the pool of available partners will worsen creating positive feedbacks and possibly multiple steady states early public health efforts may allow societies to reach more favorable steady states excerpt

investor and value line analyst underreaction to information about future earnings the corrective role of non earnings surprise information prior research suggests that financial analysts earnings forecasts and stock prices underreact to earnings news this paper provides evidence that analysts and investors correct this underreaction in response to the next earnings announcement and to other non earnings surprise information available between earnings announcements our evidence also suggests that analysts and investors underreact to information reflected in analysts earnings forecast revisions and that non earnings surprise information helps correct this underreaction as well controlling for corrective non earnings surprise information significantly increases estimates of the degree to which analysts forecasting behavior can explain drifts in returns following both earnings announcements and analysts earnings forecast revisions

who gets the job referral evidence from a social networks experiment we use recruitment into a laboratory experiment in kolkata india to analyze how job networks select individuals for employment opportunities we present evidence that individuals face a tradeoff between choosing the most qualified individual for the job and the individual who is ideal from the perspective of their social network the experiment allows randomly selected subjects to refer members of their social networks to subsequent rounds of the experiment and varies the incentive schemes offered to these participants we find that when faced with performance pay individuals are more likely to refer co workers and less likely to refer family members high ability participants who are offered performance pay recruit referrals who perform significantly better on a cognitive ability task and also prove to be more reliable as evidenced by their choices in the trust game and performance on an effort task

does meeting earnings expectations matter evidence from analyst forecast revisions and share prices this paper investigates whether the market rewards firms meeting current period earnings expectations and whether any such reward reflects the implications of meeting expectations in the current period for future earnings or reflects a distinct market premium we document that abnormal annual returns are significantly greater for firms meeting expectations controlling for the information in the current year s earnings we then test whether firms meeting expectations experience higher returns simply because their expected future earnings are also higher we find firms meeting expectations have significantly higher earnings forecasts and realized earnings than firms that do not we find that controlling for these higher future earnings firms meeting expectations in one or two years do not receive a greater valuation than their fundamentals would suggest we find however that the market assigns a higher value to firms that meet expectations consistently controlling for an estimate of the firm s fundamental value

information in the tails of the distribution of analysts quarterly earnings forecasts investors generally measure earnings announcement news on the basis of the difference between actual earnings and two salient benchmarks earnings in the same quarter the previous year and a consensus drawn from a distribution of forecasts by financial analysts we evaluate the implications of a third salient benchmark the most optimistic forecast when actual earnings exceed the consensus and the most pessimistic forecast when the consensus exceeds actual earnings we find that considering the information in these tails of the distribution of analysts earnings forecasts enhances the profitability of post earnings announcement drift strategies

meeting strangers and friends of friends how random are social networks we present a dynamic model of network formation where nodes find other nodes with whom to form links in two ways some are found uniformly at random while others are found by searching locally through the current structure of the network e g meeting friends of friends this combination of meeting processes results in a spectrum of features exhibited by large social networks including the presence of more high and low degree nodes than when links are formed independently at random having low distances between nodes in the network and having high clustering of links on a local level we fit the model to data from six networks and impute the relative ratio of random to network based meetings in link formation which turns out to vary dramatically across applications we show that as the random network based meeting ratio varies the resulting degree distributions can be ordered in the sense of stochastic dominance which allows us to infer how the formation process affects average utility in the network

social networks and the identification of peer effects there is a large and growing literature on peer effects in economics in the current article we focus on a manski type linear in means model that has proved to be popular in empirical work we critically examine some aspects of the statistical model that may be restrictive in empirical analyses specifically we focus on three aspects first we examine the endogeneity of the network or peer groups second we investigate simultaneously alternative definitions of links and the possibility of peer effects arising through multiple networks third we highlight the representation of the traditional linear in means model as an autoregressive model and contrast it with an alternative moving average model where the correlation between unconnected individuals who are indirectly connected is limited using data on friendship networks from the add health dataset we illustrate the empirical relevance of these ideas

job information networks neighborhood effects and inequality this paper explores the theoretical and empirical literature to examine the use by different social groups of informal sources of information provided by friends relatives and acquaintances during job search and its consequences for the job market it also addresses the role of network structure and size the resource endowments of contacts and nature of the links between contacts to explain differences in the effects of job information networks in doing so the paper also turns to the sociology literature on job information networks and provides an economic perspective on such sociological concepts as strong versus weak ties inbreeding distance from structural holes etc the paper distinguishes between models of exogenous job information networks that is where individuals obtain job related information through a given social structure and endogenous job information networks which are social networks that result from individuals uncoordinated actions the paper pays special attention to such issues as physical and social proximity and sharing of information and discusses them in the context of the recent social interactions and neighborhood effects literature finally the paper outlines a model that integrates job information networks where interactions occur in business cycle frequencies with the dynamics of human capital formation which include the joint effects of parental community and neighborhood human capital and are set in life cycle frequencies for the purpose of organizing suggestions for future research and examining earned income inequality

diffusion of behavior and equilibrium properties in network games situations in which agents choices depend on choices of those in close proximity be it social or geographic are ubiquitous selecting a new computer platform signing a political petition or even catching the flu are examples in which social interactions have a significant role while some behaviors or states propagate and explode within the population e g windows os the hiv virus others do not e g certain computer viruses our goal in this paper is twofold first we provide a general dynamic model in which agents choices depend on the underlying social network of connections second we show the usefulness of the model in determining when a given behavior expands within a population or disappears as a function of the environment s fundamentals we study a framework in which agents face a choice between two actions 0 and 1 e g whether to pursue a certain level of education switch to linux os etc agents are linked through a social network and an agent s payoffs from each action depend on the number of neighbors she has and her neighbors choices the diffusion process is defined so that at each period each agent best responds to the actions taken by her neighbors in the previous period assuming that her neighbors follow the population distribution of actions a mean field approximation steady states correspond to equilibria of the static game under some simple conditions equilibria take one of two forms some are stable so that a slight perturbation to any such equilibrium would lead the diffusion process to converge back to that equilibrium point other equilibria are unstable so that a slight change in the distribution of actions leads to a new distribution of actions and eventually to a stable steady state we call such equilibria tipping points we analyze how the environment s fundamentals cost distribution payoffs and network structure affect the set of equilibria and characterize the adoption patterns within the network the paper relates to recent work on network games and network diffusion including work by stephen morris 2000 pastor satorras and vespignani 2000 mark e j newman 2002 dunia lopez pintado 2004 jackson and brian w rogers 2007 jackson and yariv 2005 and andrea galeotti et al 2005 henceforth ggjvy its contribution is in characterizing diffusion of strategic behavior and analyzing the stability properties of equilibria and employing methods that allow us to make comparisons across general network structures and settings given that social networks differ substantially and systematically in structure across settings e g ethnic groups professions etc understanding the implications of social structure on diffusion is an important undertaking for a diverse set of applications

the economic consequences of social network structure we survey the literature on the economic consequences of the structure of social networks we develop a taxonomy of macro and micro characteristics of social interaction networks and discuss both the theoretical and empirical findings concerning the role of those characteristics in determining learning diffusion decisions and resulting behaviors we also discuss the challenges of accounting for the endogeneity of networks in assessing the relationship between the patterns of interactions and behaviors

tipping and the dynamics of segregation schelling dynamic models of segregation journal of mathematical sociology 1 1971 143 186 showed that extreme segregation can arise from social interactions in white preferences once the minority share in a neighborhood exceeds a tipping point all the whites leave we use regression discontinuity methods and census tract data from 1970 through 2000 to test for discontinuities in the dynamics of neighborhood racial composition we find strong evidence that white population flows exhibit tipping like behavior in most cities with a distribution of tipping points ranging from 5 to 20 minority share tipping is prevalent both in the suburbs and near existing minority enclaves in contrast to white population flows there is little evidence of nonlinearities in rents or housing prices around the tipping point tipping points are higher in cities where whites have more tolerant racial attitudes

strategic communication networks in this paper we consider situations in which individuals want to choose an action close to others actions as well as close to a payoff relevant state of nature with the ideal proximity to the common state varying across the agents before this coordination game with heterogeneous preferences is played a cheap talk communication stage is offered to players who decide to whom they reveal the private information they hold about the state the strategic information transmission taking place in the communication stage is characterized by a strategic communication network we provide a direct link between players preferences and the strategic communication network emerging at equilibrium depending on the strength of the coordination motive and the prior information structure equilibrium strategic communication networks are characterized in a very tractable way and compared in term of efficiency in general a maximal strategic communication network may not exist and communication networks cannot be ordered in the sense of pareto however expected social welfare always increases when the communication network expands strategic information transmission can be improved when group or public communication is allowed and or when information is certifiable

the rewards to meeting or beating earnings expectations abstract this paper finds that firms that meet or beat current analysts earnings expectations mbe enjoy a higher return over the quarter than firms with similar quarterly earnings forecast errors that fail to meet these expectations further such a premium to mbe although somewhat smaller exists in the cases where mbe is likely to have been achieved through earnings or expectations management the findings also indicate that the premium to mbe is a leading indicator of future performance this premium and its predictive ability are only marginally affected by whether the mbe is genuine or the result of earnings or expectations management

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

bias in european analysts earnings forecasts forecasting company earnings is a difficult and hazardous task in an efficient market where analysts learn from past mistakes there should be no persistent and systematic biases in consensus earnings accuracy previous research has already established how some single individual company characteristics systematically influence forecast accuracy so far however the effect on consensus earnings biases of a company s sector and country affiliation combined with a range of other fundamental characteristics has remained largely unexplored using data for 1993 2002 this article disentangles and quantifies for a broad universe of european stocks how the number of analysts following a stock the dispersion of their forecasts the volatility of earnings the sector and country classification of the covered company and its market capitalization influence the accuracy of the consensus earnings forecast

an experimental analysis of unanimity in public goods provision mechanisms the paper reports on an experimental investigation of four methods of allocating public goods the two basic processes studied are direct contribution and a public goods auction process both of these processes are studied with and without an additional unanimity feature the results suggest that the auction process outperforms direct contribution the effect of unanimity is to decrease the efficiency of both processes much of the paper is focused on an analysis of these results

network structure and the aggregation of information theory and evidence from indonesia abstract we use unique data from over 600 indonesian communities on what individuals know about the poverty status of others to study how network structure influences information aggregation we develop a model of semi bayesian learning on networks which we structurally estimate using within village data the model generates qualitative predictions about how cross village patterns of learning relate to network structure which we show are borne out in the data we apply our findings to a community based targeting program where citizens chose households to receive aid and show that the networks that the model predicts to be more diffusive differentially benefit from community targeting jel d14 d83 d85 i32 o12 z13

efficiency and stability of a financial architecture with too interconnected to fail institutions abstract the regulation of large interconnected financial institutions has become a key policy issue to improve financial stability regulators have proposed limiting banks size and interconnectedness i estimate a network based model of the over the counter interbank lending market in the us and quantify the efficiency stability implications of this policy trading efficiency decreases with limits on interconnectedness because the intermediation chains become longer while restricting the interconnectedness of banks improves stability the effect is non monotonic stability also improves with higher liquidity requirements when banks have access to liquidity during the crisis and when failed banks depositors maintain confidence in the banking system

arbitrage risk and post earnings announcement drift this study examines whether the magnitude of post earnings announcement drift is related to the risk faced by arbitrageurs who may view the anomaly as a trading opportunity consistent with this hypothesis the magnitude of the drift is strongly related to the arbitrage risk measure developed by wurgler and zhuravskaya 2002 the effect of arbitrage risk is statistically and economically significant in a range of specifications the results support the view of post earnings announcement drift as an underreaction to earnings information

linear social interactions models this paper provides a systematic analysis of identification in linear social interactions models this is a theoretical and econometric exercise as the analysis is linked to a rigorously delineated model of interdependent decisions we develop an incomplete information game for individual choice under social influences that nests standard models as special cases we consider identification of both endogenous and contextual social effects under alternative assumptions regarding an analyst s a priori knowledge of social structure or access to individual level or aggregate data finally we discuss potential ramifications for identification of endogenous formation of social structure

networks in labor markets wage and employment dynamics and inequality we present a model of labor markets that accounts for the social network through which agents hear about jobs we show that both wages and employment are positively associated a strong form of correlation across time and agents we also analyze the decisions of agents regarding staying in the labor market or dropping out if there are costs to staying in the labor market then networks of agents that start with a worse wage status will have higher drop out rates and there will be a persistent differences in wages between groups according to the starting states of their networks

adoption curves and social interactions this paper considers the observational implications of social influences on adoption decisions for an environment of perfect foresight adopters we argue that social influences can produce two observable effects 1 discontinuities in unconditional adoption curves and 2 pattern reversals in conditional adoption curves in which earlier adoption is found for one group of actors versus another when fundamentals suggest the reverse ordering should occur in turn the presence of either of these features can under weak assumptions be interpreted as evidence of social influences as such these properties are robust implications of social effects jel c40 d01 o33

the multiperiod information content of accounting earnings confirmations and contradictions of previous earnings reports in this study we propose and test the hypothesis that investors reevaluate earnings announcements in the light of postannouncement information 1 our argument for multiperiod price reactions to earnings news is motivated by the literature linking price responses to earnings persistence 2 when earnings are announced we assume that investors are unable to determine with certainty the persistence of an earnings

informative and persuasive campaigning in this paper we use a simple downsian spatial model to analyze the properties of campaign contributions we first consider campaign contributions that are intended to inform voters of candidate positions we show that it is difficult to construct arguments in a downsian spatial model for why some voters would choose to contribute to a candidateand the candidate would want to spend the money contributed to inform voters of his position we then define persuasive campaign expenditures as those that are intended to convince an individual to vote for a candidate regardless of the candidate s position on issues in the presence of persuasive campaign expenditures some voters have an incentive to contribute to one or both candidates and the candidates have an incentive to spend the money we show why the nature of persuasive campaign expenditures may explain both their growth in recent years and the increasing advantage of incumbency

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

a strategic model of social and economic networks we study the stability and efficiency of social and economic networks when self interested individuals can form or sever links first for two stylized models we characterize the stable and efficient networks there does not always exist a stable network that is efficient next we show that this tension persists generally to assure that there exists a stable network that is efficient one is forced to allocate resources to nodes that are not responsible for any of the production we characterize one such allocation rule the equal split rule and another rule that arises naturally from bargaining of the players

the effects of social networks on employment and inequality we develop a model where agents obtain information about job opportunities through an explicitly modeled network of social contacts we show that employment is positively correlated across time and agents moreover unemployment exhibits duration dependence the probability of obtaining a job decreases in the length of time that an agent has been unemployed finally we examine inequality between two groups if staying in the labor market is costly and one group starts with a worse employment status then that group s drop out rate will be higher and their employment prospects will be persistently below that of the other group

spatial versus social mismatch the aim of this paper is to provide a new mechanism based on social interactions explaining why distance to jobs can have a negative impact on workers labor market outcomes especially ethnic minorities building on granovetter s idea that weak ties are superior to strong ties for providing support in getting a job we develop a model in which workers who live far away from jobs choose to have less connections to weak ties because of the lack of good public transportation in the us it is costly both in terms of time and money to commute to business centers to meet other types of people who can provide other source of information about jobs if distant minority workers mainly rely on their strong ties who are more likely to be unemployed there is then little chance for them of escaping unemployment it is therefore the separation in both the social and physical space that prevents ethnic minorities from finding a job

experimental games on networks underpinnings of behavior and equilibrium selection in this paper we describe a series of laboratory experiments that implement specific examples of a general network structure specifically actions are either strategic substitutes or strategic complements and participants have either complete or incomplete information about the structure of a random network since economic environments typically have a considerable degree of complementarity or substitutability this framework applies to a wide variety of settings we examine behavior and equilibrium selection the degree of equilibrium play is striking in particular with incomplete information behavior closely resembles the theoretical equilibrium whenever this is unique when there are multiple equilibria general features of networks such as connectivity clustering and the degree of the players help to predict informed behavior in the lab people appear to be strongly attracted to maximizing aggregate payoffs social efficiency but there are forces that moderate this attraction 1 people seem content with in the aggregate capturing only the lion s share of the efficient profits in exchange for reduced exposure to loss and 2 uncertainty about the network structure makes it considerably more difficult to coordinate on a demanding but efficient equilibrium that is typically implemented with complete information

networks in the modern economy mexican migrants in the u s labor market this paper attempts to identify job networks among mexican migrants in the u s labor market the empirical analysis uses data on migration patterns and labor market outcomes based on a sample of individuals belonging to multiple origin communities in mexico over a long period of time each community s network is measured by the proportion of the sampled individuals who are located at the destination the united states in any year we verify that the same individual is more likely to be employed and to hold a higher paying nonagricultural job when his network is exogenously larger by including individual fixed effects in the employment and occupation regressions and by using rainfall in the origin community as an instrument for the size of the network at the destination

the impact of social structure on economic outcomes s ocial structure especially in the form of social networks affects economic outcomes for three main reasons first social networks affect the flow and the quality of information much information is subtle nuanced and difficult to verify so actors do not believe impersonal sources and instead rely on people they know second social networks are an important source of reward and punishment since these are often magnified in their impact when coming from others personally known third trust by which i mean the confidence that others will do the right thing despite a clear balance of incentives to the contrary emerges if it does in the context of a social network economists have recently devoted considerable attention to the impact of social structure and networks on the economy for example see the economists chapters in rauch and casella 2001 and the illuminating review essay of this volume by zuckerman 2003 as well as dutta and jackson 2003 and calvoarmengol 2004 however i focus here on sociologists contributions sociologists have developed core principles about the interactions of social structure information ability to punish or reward and trust that frequently recur in their analyses of political economic and other institutions i begin by reviewing some of these principles building on these i then discuss how social structures and social networks can affect economic outcomes like hiring price productivity and innovation