the importance of firm wage differentials in explaining hourly earnings variation in the large scale sector of guatemala abstract i utilize unique firm based data to examine firm wage differentials among private firms with ten or more workers in the capital area of guatemala city approximately one seventh of the overall hourly earnings variation in this sector is related to firm effects not captured by other observable characteristics of individuals and firms for most variables including observable characteristics of firms used in most previous studies the bias from not including firm fixed effects in the estimation of log wage equations is small in magnitude though statistically significant

the low skill trap recently it has become popular to argue that certain workers have fallen into a trap in which they have poor skills few job opportunities and a low return on training while others have not this paper demonstrates how such a trap can occur within a simple matching model with rent sharing rent sharing diminishes the worker s incentive to acquire skills however since firms also benefit from training rent sharing likewise induces job creation the subsequent improved matching prospects may offset the initial disincentive to invest however for this mechanism to be effective firms and workers must coordinate their actions if they do not the trap occurs

ambiguous volatility and asset pricing in continuous time we formulate a model of utility for a continuous time framework that captures aversion to ambiguity about both volatility and drift corresponding extensions of some basic results in asset pricing theory are presented first we derive arbitrage free pricing rules based on hedging arguments because ambiguous volatility implies market incompleteness hedging arguments determine prices only up to intervals in order to obtain sharper predictions we apply the model of utility to a representative agent endowment economy and study equilibrium asset returns a version of the consumption capital asset pricing model is derived and the effects of ambiguous volatility are described the author 2013 published by oxford university press on behalf of the society for financial studies all rights reserved for permissions please e mail journals permissions oup com oxford university press

finding a maximum skewness portfolio a general solution to three moments portfolio choice considering the three first moments and allowing short sales the efficient portfolios set for n risky assets and a riskless one is found supposing that agents like odd moments and dislike even ones analytical formulas for the solution surface are obtained and important geometric properties provide insights on its shape in the three dimensional space defined by the moments a special duality result is needed and proved the methodology is general comprising situations in which for instance the investor trades a negative skewness for a higher expected return computation of the optimum portfolio weights is feasible in most cases

the dynamics of monopoly union wages with asymmetric information dunlop s 1994 work on the monopoly union model emphasizes that the primary role of wages is to distribute industry rents this paper extends the model to two periods and it is furthermore assumed that firms are better informed than workers about the size or quality of capital this variable is unchanged over time so the firm s first period action signals information relevant for the second period wage this dynamic relationship tends to lower labour demand in the first period

the pricing of options on assets with stochastic volatilities one option pricing problem that has hitherto been unsolved is the pricing of a european call on an asset that has a stochastic volatility this paper examines this problem the option price is determined in series form for the case in which the stochastic volatility is independent of the stock price numerical solutions are also produced for the case in which the volatility is correlated with the stock price it is found that the black scholes price frequently overprices options and that the degree of overpricing increases with the time to maturity one option pricing problem that has hitherto remained unsolved is the pricing of a european call on a stock that has a stochastic volatility from the work of merton 12 garman 6 and cox ingersoll and ross 3 the differential equation that the option must satisfy is known the solution of this differential equation is independent of risk preferences if a the volatility is a traded asset or b the volatility is uncorrelated with aggregate consumption if either of these conditions holds the risk neutral valuation arguments of cox and ross 4 can be used in a straightfoward way this paper produces a solution in series form for the situation in which the stock price is instantaneously uncorrelated with the volatility we do not assume that the volatility is a traded asset also a constant correlation between the instantaneous rate of change of the volatility and the rate of change of aggregate consumption can be accommodated the option price is lower than the blackscholes b s 1 price when the option is close to being at the money and higher when it is deep in or deep out of the money the exercise prices for which overpricing by b s takes place are within about ten percent of the security price this is the range of exercise prices over which most option trading takes place so we may in general expect the b s price to overprice options this effect is exaggerated as the time to maturity increases one of the most surprising implications of this is that if the b s equation is used to determine the implied volatility of a near the money option the longer the time to maturity the lower the implied volatility numerical solutions for the case in which the volatility is correlated with the stock price are also examined the stochastic volatility problem has been examined by merton 13 geske 7 johnson 10 johnson and shanno 11 eisenberg 5 wiggins 16 and

incentives pay and performance a study of australian employees the paper analyses the determinants of self reported work effort using a 1988 survery of australian employees while controlling for the endogeneity of the firm s choice of incentives and pay it is found that direct incentive schemes have predicted effects and the efficiency wage hypothesis is supported pay and work effort are positively correlated two efficiency wage models are tested akerlof s gift exchange model and work discipline arguments regarding monitoring difficulties and threats of dismissal the latter argument is broadly consistent with the data

comonotonic approximation to periodic investment problems under stochastic drift abstract we investigate periodic investment problems under a black scholes market with stochastic drift the decision maker invests a series of positive amounts at finitely predetermined time spots to maximize the expected terminal wealth while controlling its downside risk as measured by the condition value at risk cvar it turns out that the increment for unit wealth on the whole path can be divided into two parts the increment corresponding to the stochastic drift and that corresponding to the brownian motion a comonotonic approximation is proposed for the second part and an upper bound is provided for the cvar of the first part which construct together a closed form approximation of the terminal wealth under the risk measure of cvar we further decompose the problem into a sequence of sub problems whose optimal solutions are explicit and follow fractional kelly strategy numerical and empirical results illustrate the performance of our methodology

moral hazard in dynamic risk management we consider a contracting problem in which a principal hires an agent to manage a risky project when the agent chooses volatility components of the output process and the principal observes the output continuously the principal can compute the quadratic variation of the output but not the individual components this leads to moral hazard with respect to the risk choices of the agent to find the optimal contract we develop a novel approach to solving principal agent problems first we identify a family of admissible contracts for which the optimal agent s action is explicitly characterized then we show that we do not lose on generality when finding the optimal contract inside this family up to integrability conditions to do this we use the recent theory of singular changes of measures for ito processes we solve the problem in the case of cara preferences and show that the optimal contract is linear in these factors the contractible sources of risk including the output the quadratic variation of the output and the cross variations between the output and the contractible risk sources thus like sample sharpe ratios used in practice path dependent contracts naturally arise when there is moral hazard with respect to risk management in a numerical example we show that the loss of efficiency can be significant if the principal does not use the quadratic variation component of the optimal contract

efficiency wage models of unemployment one view h lorne carmichael persistent wage rigidity and involuntary unemployment appear to be recurrent problems in most economies what could be preventing the wage adjustment necessary to clear the labor market many recent papers claim to have found the answer in efficiency wage models this paper surveys this literature and attempts to evaluate its accomplishments it concludes that the efficiency wage models fail to explain wage rigidity or persistent involuntary unemployment persistent involuntary unemployment of workers is a recurrent problem in labor markets all over the world unemployed workers seem unable to find work even though they are willing to accept lower wages than those being paid employed workers with similar skills what could be preventing wages from adjusting to clear these markets many recent papers known collectively as the efficiency wage literature now claim to have the answer this paper will survey the efficiency wage literature and critically evaluate some of its accomplishments efficiency wage models have already been examined by yellen 1984 katz 1986 and stiglitz 1987 and have received generally favorable reviews this paper is more critical its overall conclusion is that efficiency wage models provide some useful insights into the workings of the labor market but they do not provide a satisfactory account of wage rigidity or involuntary unemployment there are at least five separate versions of the efficiency wage model they share a common structure however and this is outlined in the first section of the paper this section also attempts to relate efficiency wage models to other recent models of unemployment section ii examines and criticizes the different approaches in detail section iii evaluates the achievements of this approach and suggests some directions for future work i a general efficiency wage model efficiency wage models as the name suggests are first of all models of wages they generate unemployment by showing that firms will sometimes want to set wages at non market clearing levels it is useful to begin therefore by reviewing how wages and employment are determined in some related models in a perfectly competitive labor market the wage for each type of labor is adjusted constantly to maintain equality of supply and demand overall employment fluctuates in response to demand changes as workers move up and down their labor supply curves unemployment is voluntary in that anyone who is not working prefers that state to employment at the going wage for people of his skills as well the value of a worker s marginal product is equal to the marginal value of his leisure so there are no unexploited wage bargains between unemployed workers and firms this model is successful in predicting the long term response of wages to shifts in demand and supply but it is clear that in the short run its depiction of voluntary unemployment and flexible wages is unrealistic a natural way to generate more realism is to assume that wages are inflexible in the short run in this case a reduction in demand away from a long run equilibrium will lead to rationing of jobs by employers as they attempt to stay on their labor demand curves the unemployment here is involuntary in that the unemployed would prefer to be working at the going wage and is inefficient in that there are lost gains from trade between these workers and firms the weakness of this model is that it is silent about the mechanism that keeps wages rigid unemployed workers who offer to work for less than the fixed wage ought to find work the early implicit contract models of azariadis 1975 baily 1974 and gordon 1974 provide one explanation for wage rigidity these models introduced the idea that wages can do more than just clear the market for labor wages in an implicit contract model are used to shift the risk generated by uncertain output market conditions from risk averse workers to the risk neutral firm

does high frequency crude oil futures data contain useful information for predicting volatility in the us stock market new evidence abstract this study examines whether high frequency crude oil futures data contain useful information to forecast the realized volatility rv of the us stock market from both in and out of sample perspectives there are several significant findings first from the in sample analysis crude oil futures rv exhibits a significant positive impact on the future s p 500 volatility second the out of sample results reveal that the prediction models including crude oil futures rv outperform the related competing models implying that crude oil rv is an important predictive factor for the us stock market third we further find that the primary forecasting ability of crude oil rv is reflected in high frequency information negative crude oil rv and high volatility level finally the out of sample empirical results based on different forecasting windows alternative forecast evaluation approaches subsample analysis different prediction models alternative midas lags and controlling the leverage effect are robust to our conclusions

mean var portfolio optimization a nonparametric approach portfolio optimization involves the optimal assignment of limited capital to different available financial assets to achieve a reasonable trade off between profit and risk we consider an alternative markowitz s mean variance model in which the variance is replaced with an industry standard risk measure value at risk var in order to better assess market risk exposure associated with financial and commodity asset price fluctuations realistic portfolio optimization in the mean var framework is a challenging problem since optimizing var leads to a non convex np hard problem which is computationally intractable in this work an efficient learning guided hybrid multi objective evolutionary algorithm mode gl is proposed to solve mean var portfolio optimization problems with real world constraints such as cardinality quantity pre assignment round lot and class constraints a learning guided solution generation strategy is incorporated into the multi objective optimization process to promote efficient convergence by guiding the evolutionary search towards promising regions of the search space the proposed algorithm is compared against the non dominated sorting genetic algorithm nsga ii and the strength pareto evolutionary algorithm spea2 experimental results using historical daily financial market data from s p 100 and s p 500 indices are presented experimental results shows that mode gl outperforms two existing techniques for this important class of portfolio investment problems in terms of solution quality and computational time the results highlight that the proposed algorithm is able to solve the complex portfolio optimization without simplifications while obtaining good solutions in reasonable time and has significant potential for use in practice

fair wages in the open economy we show how an extended theory of fair wages can be incorporated in the two by two heckscher ohlin model an important feature of the model is the existence of involuntary unemployment several results stand out first there is no longer a simple relatio

competition privatisation and productive efficiency evidence from the airline industry we use data from the airline industry to examine the extent to which the costs of airline operations are affected by rents accruing to workers and the extent to which these rents depend inter alia upon the degree of competition in the industry our empirical results based on a panel of twelve european and seven major united states airlines confirm that state ownership substantially increases rents to labour while the effects of competition are more subtle and ambiguous airline profits tend to be associated with higher rents to employees the gains from further privatisation and liberalisation may be quite large does competition have significant effects on productive as well as allocative efficiency convincing empirical answers to this question have been hard to find for two reasons first data of the quality required for robust estimation of productive efficiency are only rarely available secondly there is frequently no convincing standard against which the efficiency of an industry or a firm may be compared since when the degree of competition varies many other things such as technology network structures and firm sizes typically vary as well these problems do not automatically make comparison impossible but they compound the need for high quality data one industry which is likely to be well suited to investigating questions of this kind is the international airline industry the industry contains a large number of firms thus ensuring at least enough potential competition to make questions about the effects of competition interesting but the scope for these firms to compete with one another has been influenced to varying degrees over the years by different national and international regulatory regimes in particular deregulation of the united states industry in 1978 provided a kind of natural experiment that has led not only to comparisons of the before and after variety but also to comparisons between the united states industry and that of other global regions notably europe such comparisons are far from straightforward but they are facilitated by the fact that the technology of civil aviation is more or less internationally standardised and by the relatively high quality of available data in the industry

the decline of discrimination against colored people in south africa 1970 to 1980 abstract the paper analyses the gap in earnings between white and colored people in south africa in 1970 and 1980 the gap is decomposed into its explained and discrimination components and from a model of occupational attainment into wage and job discrimination job discrimination decreased between 1970 and 1980 colored people in younger experience cohorts experienced a significant decline in discrimination between 1970 and 1980 most of which was due to a decline in job descrimination discrimination against those in older experience cohorts appears not to have declined

on the sensitivity of mean variance efficient portfolios to changes in asset means some analytical and computational results tbis paper investigates the sensitivity of meanvariance mv efficientportfolios to changes in the means of individual assets when only a budget constraint is imposed on the investment problem the analytical results indicate that an mv efficient portfolio s weights mean and variance can be extremely sensitive to cbanges in asset means when nonnegativity constraints are also imposed on the problem the computational results confirm that a positively weigbted mv efficient portfolio s weigbts are extremely sensitive to cbanges in asset means but the portfolio s returns are not a surprisingly small increase in the mean of just one asset drives balf the securities from the portfolio yet the portfolio s expected return and standard deviation are virtually uncbanged this paper supersedes should investors hold well diversified portfolios financial support from the natural science and engineering research council of canada is gratefully acknowledged we also acknowledge the most capable assistance of ruth cornale simon ng jean marc potier and frederick shen the paper was presented at simon fraser university and the western finance association meetings in san diego we thank the participants especially stephen brown john herzog john heaney ray koopman and bruce lehmann and the editors jon ingersoll and chester spatt for

horizon unbiased investment with ambiguity abstract in the presence of ambiguity about the driving force of market randomness we consider a dynamic portfolio choice problem without any predetermined investment horizon the investment criterion is formulated as a robust forward performance process reflecting an investor s dynamic preference adapted to the market evolution we show that the market risk premium and the utility risk premium jointly determine the investors trading direction and the worst case scenarios of the risky asset s mean return and volatility the closed form solution for the optimal investment strategies is given in the special settings of the constant relative risk aversion crra preference the resulting portfolio strategies highlight the effect of ambiguity on nonparticipation in the risky asset market from the forward performance point of view

trade protection and industry wages in india this paper examines the link between trade protection and industry wage premia in india using a unique dataset combining employment survey data with industry level data for various years between 1983 and 2000 the author finds that india s trade reforms were not distributionally neutral the impact of protection on industry wage premia was positive and statistically significant though modest in magnitude workers employed in industries with high tariffs received higher wages than apparently identical workers in low tariff industries because industries with high initial levels of protection were also those with the largest tariff reductions during this period and had the highest share of unskilled workers the positive tariff wage effect implies that the trade reforms were likely to have increased wage inequality as the relative wages of the predominantly unskilled workers in these manufacturing industries fell

bayes stein estimation for portfolio analysis in portfolio analysis uncertainty about parameter values leads to suboptimal portfolio choices the resulting loss in the investor s utility is a function of the particular estimator chosen for expected returns so this is a problem of simultaneous estimation of normal means under a well specified loss function in this situation as stein has shown the clas sical sample mean is inadmissible this paper presents a simple empirical bayes estimator that should outperform the sample mean in the context of a portfolio simulation analysis shows that these bayes stein estimators provide significant gains in portfolio selection problems

efficiency wage models of unemployment a second view kevin lang and shulamit kahn efficiency wage models in which firms find it profitable to pay wages above workers reservation wages provide a promising explanation for unemployment and interindustry wage differentials one criticism of such models is they imply firms should sell jobs by requiring up front bonds from new workers however only some efficiency wage models imply this moreover firms might not require bonds for many reasons we show that moral hazard and adverse selection models together explain many labor market phenomena the efficiency wage model conforms well to empirical finding but certain anomalies suggest the need to consider rent sharing models carmichael s paper in this volume is an important contribution to the debate over the importance of efficiency wages he clearly outlines some of the deficiencies in the theory and thus points out areas needing further research nevertheless his conclusions are far too negative he greatly exaggerates the theoretical weakness of the efficiency wage model and gives insufficient recognition to the empirical implications generated by this model and to tests of these implications i shirking models there is direct empirical evidence that shirking is a serious problem for firms firms spend significant sums monitoring workers levine 1987 reviews the evidence that worker shirking is widespread and costly the evidence in burroway 1979 and mars 1982 also demonstrates the importance of shirking and stealing carmichael s primary argument against shirking models is that if the payment of efficiency wages to deter shirking led to an excess supply of workers workers would buy their jobs by posting bonds since we do not observe workers posting bonds he concludes that firms do not pay efficiency wages either given the importance of shirking the absence of market clearing bonds needs explaining one explanation is that the market has found some reasonable substitute for bonds such as deferred wage payments it is theoretically feasible to substitute deferred wage payments for up front bonds as noted by akerlof and katz 1989 however the empirical evidence of industries with deferred payments i e where low beginning wages are balanced by high subsequent wages is mixed dickens and katz 1987b krueger and summers 1988 and abraham and farber 1987 indicate that industries which pay high wages to high tenure workers tend to pay high wages to low tenure workers on the other hand high wage industries also tend to have steeper earnings profiles which may be evidence of deferred earnings in these industries as shapiro and stiglitz 1984 note a second possible explanation for the absence of market clearing bonding is that bonding gives firms an incentive to fire workers immediately upon collecting their bonds however this explanation assumes that a firm will immediately fire every worker who posts a bond if there are any reputation costs at all some firms sometimes will not fire bond posting workers and we should observe some bonding yet with finite length contracts there must be some reputation costs because otherwise firms would never pay workers in the last period thus firm incentives to cheat and fire workers cannot explain the complete absence of bonding clearly the absence of market clearing bonding is not fully understood and further theoretical work is needed dickens katz lang and summers 1989 review a wide variety of possible reasons that bond posting is limited the important point is that there are many potential reasons for limited bonding other than the absence of efficiency wages on the other hand the lack of bonding despite the importance of shirking does not demonstrate that firms pay efficiency wages there may be reputation or other costs to the worker caught shirking even in the absence of bonding as dickens katz lang and summers 1989 demonstrate in the absence of bonding whether paying efficiency wages dominates relying solely on increased monitoring depends on the parameters of the model and is therefore an empirical issue

an introduction to the wage curve en conomists and policymakers are interested in understanding the forces that determine the level of unemployment and the level of wages this paper describes an empirical discovery made with the help of international microeconometric evidence covering more than a dozen nations about a link between these two variables the connection can be portrayed on a graph with the level of unemployment on the horizontal axis and the level of wages on the vertical axis then the wage curve as shown in figure 1 is a downwardsloping locus this relationship tells us that holding others things constant if a region has a rise in unemployment in a particular year those who live there will have a fall in their wages in that year what does this curve mean how in a field where fully controlled experiments are almost impossible could there be any convincing scientific basis for this wage curve what is the relationship between the wage curve and a phillips curve other than that the curve of figure 1 looks like a phillips curve with the vertical axis mislabeled how does the wage curve fit into existing economic knowledge and is the empirical finding consistent with competitive theory this paper sketches answers to these kinds of questions the discussion draws on our book the wage curve blanchflower and oswald 1994 where the points raised here are investigated more fully it also rests upon work done by other economists whose work is listed in the paper and the bibliography

contractual wages and the wage cushion under different bargaining settings how does a typically european bargaining system with collective bargaining and national minimum wage coexist with low unemployment and high wage flexibility a unique data set on workers firms and collective bargaining contracts in portugal is used to analyze the determinants of both the contractual wage and the wage cushion difference between contractual and actual wages the results indicate that the wage cushion stretches the returns to worker and firm attributes whereas it shrinks the returns to union power therefore firm specific arrangements partly offset collective bargaining granting firms certain freedom when setting wages contractual wages reflect trade unions egalitarian policy

industry wage differentials and efficiency wages a dissenting view with south african evidence abstract does industry wage dispersion constitute evidence of either efficiency wages or rent sharing comparison of the industry wage premia of whites and africans in south africa casts doubt upon the rent extraction and the gift exchange explanations of the industry wage structure unions combined with union threats fail to explain the data other explanations unobserved ability compensating differentials and the shirking monitoring and turnover models are rejected here as they have been before remaining possibilities are expense preference theory and internal equity rules implications for future research are pointed out

rent sharing holdup and wages evidence from matched panel data rent sharing by workers can reduce the incentives for investment if some of the returns to sunk capital are captured in higher wages we propose a simple measure of this holdup effect based on the size of the wage offset for firm specific capital accumulation using social security earnings records for workers in the veneto region of italy linked to detailed financial data for their employers we find strong evidence of rent sharing with an elasticity of wages with respect to potential rents per worker of around 4 arising mainly at larger firms with higher price cost margins on the other hand we find little evidence that bargaining lowers the return on investment instead firm level bargaining appears to split the rents after deducting the full cost of capital

simple binomial processes as diffusion approximations in financial models a binomial approximation to a diffusion is defined as computationally simple if the number of nodes grows at most linearly in the number of time intervals it is shown how to construct computationally simple binomial processes that converge weakly to commonly employed diffusions in financial models the convergence of the sequence of bond and european option prices from these processes to the corresponding values in the diffusion limit is also demonstrated numerical examples from the constant elasticity of variance stock price and the cox ingersoll and ross 1985 discount bond price are provided article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

wage differentials in brazil theory and evidence the investigation of wage determination and wage differentials in developing countries has concentrated on the effects of human capital and different sources of segmentation associated with institutional arrangements and structural characteristics on earnings in this article we use micro data for brazil for the 1980s and 1990s to test several competitive theories and models with segmentation explained by efficiency wages we find that unmeasured abilities and efficiency wage models seem to play a role in wage determination while compensating differentials and transitory difference theories were found to be irrelevant to wages formation

forecasting stock return variance toward an understanding of stochastic implied volatilities we examine the behavior of measured variances from the options market and the underlying stock market under the joint hypotheses that markets are informationally efficient and that option prices are explained by a particular asset pricing model forecasts from time series models of the stockreturn process should not have predictive content given the market forecast as embodied in option prices both in sample and out of sample tests suggest that this hypothesis can be rejected using simulations we show that biases inherent in the procedure we use to imply variances cannot explain this result thus we provide evidence inconsistent with the orthogonality restrictions of option pricing models that assume that variance risk is unpriced these results also have implicationsfor optimal variance forecast rules

dynamic resource allocation with hidden volatility abstract we study a firm s internal resource allocation using a dynamic principal agent model with endogenous cash flow volatility the principal supplies the agent with resources for productive use but the agent has private control over both project volatility and resource intensity and may misallocate resources to obtain private benefits the optimal contract can yield either overly risky or overly prudent project selection it can be implemented with a constant pricing schedule i e a static decentralized linear mechanism giving the agent control over the resource quantities project risk and agent s equity share the implementation rationalizes the use of hurdle rates above a firm s cost of capital and transfer prices above marginal cost while showing that hurdle rates or transfer prices may not vary with the agent s risk choice

60 years of portfolio optimization practical challenges and current trends abstract the concepts of portfolio optimization and diversification have been instrumental in the development and understanding of financial markets and financial decision making in light of the 60 year anniversary of harry markowitz s paper portfolio selection we review some of the approaches developed to address the challenges encountered when using portfolio optimization in practice including the inclusion of transaction costs portfolio management constraints and the sensitivity to the estimates of expected returns and covariances in addition we selectively highlight some of the new trends and developments in the area such as diversification methods risk parity portfolios the mixing of different sources of alpha and practical multi period portfolio optimization

a linearized value at risk model with transaction costs and short selling abstract though value at risk var has been widely applied by finance industry a possibility of multiple optimums that is caused by the nonlinearity in modeling can challenge its application to deal with this technical issue we propose a linearized var model that employs the mixed 0 1 programing in lin 2009 p4 model we further advance the previous models with considering various transaction costs and the optimization of short selling weights we compare the performance of buy and hold bh strategy the mean variance mv model the original p4 model and our linearized p4 lp4 model by rebalancing a wide scale of international and alternative investments during a period between 2001 and 2012 the results of numerical tests show the superior performance of the var models to the bh and the mv portfolios the lp4 model yields the global optimum and outperforms the corresponding p4 model in both return and risk the stability of portfolio value generated from the lp4 model supports its higher effectiveness in risk management than the p4 model

real wage determination and rent sharing in collective bargaining agreements the microeconomic forces that influence real wages are not fully understood this paper studies pay determination using data on approximately 600 labour contracts it finds that the real wage is an increasing function of past profitability in the employer s industry and a decreasing function of the level of unemployment in the employer s region these results are consistent with rent sharing theories

wages and profits in manufacturing firms matched panel evidence from brazil we provide evidence about the determinants of the wage structures of developing countries by examining the case of brazil our specific question is whether brazil s dramatic income and wage dierentials can be explained by the division of rents between firms and their employees unlike in competitive labour markets using detailed individual level matched panel data covering a large share of manufacturing firms and more than 30 million workers between 1997 and 2002 we consider the endogeneity of profits by adopting dierent measures of profits and dierent instruments and by controlling for spell fixed eects our results robust to dierent specifications and tests indicate no evidence of rent sharing this conclusion contrasts with findings for most developed countries even those with flexible labour markets possible explanations for the lack of rent sharing include the weakness of labour market institutions the high levels of worker turnover and the macroeconomic instability faced by the country

micro foundations for wage flexibility wage insurance at the firm level to what extent do firms insulate their workers wages from fluctuations in product markets which firm and worker attributes are associated with wage flexibility at the micro level we first rely on guiso pistaferri and schivardi 2005 to estimate dynamic models of sales and wages finding that in portugal workers wages respond to permanent shocks on firm performance as opposed to transitory shocks we then explore the factors associated with wage flexibility finding that collective bargaining and minimum wages are associated with higher wage insurance by the firm while the threat of firm bankruptcy reduces it managers receive less protection against permanent shocks than other workers

optimal consumption and portfolio policies when asset prices follow a diffusion process abstract we consider a consumption portfolio problem in continuous time under uncertainty a martingale technique is employed to characterize optimal consumption portfolio policies when there exist nonnegativity constraints on consumption and on final wealth we also provide a way to compute and verify optimal policies our verification theorem for optimal policies involves a linear partial differential equation unlike the nonlinear partial differential equation of dynamic programming the relationship between our approach and dynamic programming is discussed we demonstrate our technique by explicitly computing optimal policies in a series of examples in particular we solve the optimal consumption portfolio problem for hyperbolic absolute risk aversion utility functions when the asset prices follow a geometric brownian motion the optimal policies in this case are no longer linear when nonnegativity constraints on consumption and on final wealth are included by these examples one can see that our approach is much easier than the dynamic programming approach

bayesian and capm estimators of the means implications for portfolio selection abstract this paper compares active investment policies under three alternative models for estimating expected stock returns the historical sample mean a shrinkage or bayesian estimator and a capm based estimator the out of sample performance of actively managed u s industry portfolios is analyzed for these three estimators over the period 1931 to 1987 it is found that the classical method based on historical means and covariances leads to the worst forecasts and out of sample performance and is generally outperformed by shrinkage estimators an active portfolio with expected returns based on the capm produced the best results among all actively managed portfolios this strategy as we show closely matches a simple buy and hold the market rule

insurance within the firm we evaluate the allocation of risk between firms and their workers using matched employer employee panel data unlike previous contributions this paper focuses on idiosyncratic shocks to the firm which are the correct empirical counterpart of the theoretical notion of diversifiable risk we allow for both temporary and permanent shocks to output and find that firms absorb temporary fluctuations fully but insure workers against permanent shocks only partially risk sharing considerations can account for about 15 percent of overall earnings variability the remainder originating from idiosyncratic shocks to individual workers our welfare calculations indicate that firms are an important vehicle of insurance provision

unions and interindustry wage differentials abstract we investigate the importance of trade unions in collective bargaining in the context of a developing country manufacturing labor market the methodology we adopt to estimate wage differentials follows the method proposed by haisken denew j p and schmidt c m 1997 review of economics and statistics 79 516 521 since it improves on the standard procedure popularized by krueger a b and summers l h 1988 econometrica 56 193 259 our findings indicate that wage dispersion is far greater in the unionized sector of brazilian manufacturing in contrast to evidence from other countries

multivariate dependence and portfolio optimization algorithms under illiquid market scenarios we propose a model for optimizing structured portfolios with liquidity adjusted value at risk lvar constraints whereby linear correlations between assets are replaced by the multivariate nonlinear dependence structure based on dynamic conditional correlation t copula modeling our portfolio optimization algorithm minimizes the lvar function under adverse market circumstances and multiple operational and financial constraints when we consider a diversified portfolio of international stock and commodity market indices under multiple realistic portfolio optimization scenarios the obtained results consistently show the superiority of our approach relative to other competing portfolio strategies including the minimum variance risk parity and equally weighted portfolio allocations

a note on robustness in merton s model of intertemporal consumption and portfolio choice abstract the paper presents a robust version of a simple two assets merton 1969 review of economics and statistics 51 247 57 model where the optimal choices and the implied shadow market prices of risk for a representative robust decision maker rdm can be easily described with the exception of the log utility case precautionary behaviour is induced in the optimal consumption investment rules through a substitution of investment in risky assets with both current consumption and riskless saving for the log utility case precautionary behaviour arises only through a substitution between risky and riskless assets on the financial side the decomposition of the market price of risk in a standard consumption based component and a further price for model uncertainty risk which is positively related to the robustness parameter is independent of the underlying risk aversion parameter

dynamic portfolio optimization with transaction costs heuristics and dual bounds we consider the problem of dynamic portfolio optimization in a discrete time finite horizon setting our general model considers risk aversion portfolio constraints e g no short positions return predictability and transaction costs this problem is naturally formulated as a stochastic dynamic program unfortunately with nonzero transaction costs the dimension of the state space is at least as large as the number of assets and the problem is very difficult to solve with more than one or two assets in this paper we consider several easy to compute heuristic trading strategies that are based on optimizing simpler models we complement these heuristics with upper bounds on the performance with an optimal trading strategy these bounds are based on the dual approach developed in brown et al brown d b j e smith p sun 2009 information relaxations and duality in stochastic dynamic programs oper res 58 4 785 801 in this context these bounds are given by considering an investor who has access to perfect information about future returns but is penalized for using this advance information these heuristic strategies and bounds can be evaluated using monte carlo simulation we evaluate these heuristics and bounds in numerical experiments with a risk free asset and 3 or 10 risky assets in many cases the performance of the heuristic strategy is very close to the upper bound indicating that the heuristic strategies are very nearly optimal this paper was accepted by dimitris bertsimas optimization

the size and sources of economic rents in a developing country manufacturing labour market the potential sources of rent to labor in a developing country urban labor market are considered in this paper the data set used enables the relative importance of unions firm size profitability ownership and firm age to be assessed on the basis of cross section evidence it is shown that all these factors affect earnings a panel data based estimation of the importance of the profitability term provides strong support for a rent sharing theory of wage determination in a developing country similar to much recent evidence for developed country labor markets copyright 1996 by royal economic society

explaining african economic performance africa has had slow growth and a massive exodus of capital in many respects it has been the most capital hostile region we review and interpret the aggregate level and microeconomic literatures to identify the key explanations for this performance there is a reasonable correspondence of the two sets of evidence pointing to four factors as being important these are a lack of openness to international trade a high risk environment a low level of social capital and poor infrastructure these problems are to a substantial extent attributable to government behaviour and the paper includes a review of the political economy literature which addresses that behaviour

the reemergence of segmented labor market theory according to dual labor market theory the labor market can be usefully described as consisting of two sectors a high wage primary sector with good working conditions stable employment and substantial returns to human capital variables such as education and experience and a low wage secondary sector with the opposite characteristics moreover primary jobs are rationed that is not all workers who are qualified for primary sector jobs and desire one can obtain one finally the sector of the labor market in which an individual is employed directly influences his or her tastes behavior patterns and cognitive abilities thus the dual labor market model or more generally segmented labor market models is simultaneously a description of the income distribution a claim about the absence of market clearing and a radical departure from the standard neoclassical assumption of fully rational actors and exogenously determined preferences while this last element is potentially the most interesting even its proponents fail to give it the attention it deserves and related work has not been incorporated into the segmented labor market model in this paper we therefore concentrate on the first two elements of the model segmented labor market theory was sufficiently popular in the late 1960 s and early 1970 s to be taken seriously by prominent mainstream labor economists however two influential and largely negative reviews glenn cain 1976 michael wachter 1974 portrayed the segmented labor market hypothesis as largely atheoretical and based at best on questionable statistical analysis it seems fair to say that even sympathetic mainstream critics felt that key insights from the segmented labor model could be incorporated into neoclassical analysis and that the remaining elements of the model did not form a sufficiently coherent theory to pose a challenge to the neoclassical model whatever the merits of this perception it is clear that advocates of the segmented labor market approach did not develop a formal theory which conformed to the standards of mainstream economists with some notable exceptions michael piore 1975 david gordon 1972 the work was atheoretical moreover the empirical methods used tended to fall outside the norm for example interviews observational studies and historical and institutional analysis advocates of the segmented labor market perspective mostly radical political economists chose instead to develop their own research program outside the mainstream the reemergence of segmented labor market theory is linked with the reversal of these two tendencies the theory has been pursued by economists using modern tools of imperfect information theory and state of the art econometrics as a result the approach has again attracted the attention of the mainstream even a few years ago it would have been a clairvoyant observer who predicted that lawrence summers would be working on a theoretical model of labor market duality with jeremy bulow 1986 that robert solow would count among his recent work a dual market model with ian mcdonald 1985 and that james heckman would publish an article in which he undertook an empirical test of a dual market model failed to reject the model and then devoted much of the rest of the article to attacking his and other tests of the dual labor market view see his article with v joseph hotz 1986 since the theoretical developments are largely associated with efficiency wage and departments of economics university of california berkeley ca 94720 and nber and boston university 270 bay state road boston ma 02215 and nber respectively this study was supported in part by nsf grant no ses 8606139 lang acknowledges support from a sloan faculty research fellowship dickens acknowledges support from the institute of industrial relations at berkeley

international portfolio diversification with estimation risk international portfolio diversification has long been advocated as a way of enhancing average returns while reducing portfolio risk for the investor who considers diversifying into foreign securities this proposition however relies on the assumption that the required inputs to the classical mean variance analysis are known with certainty typically expected returns variances and covariances are simply replaced by their ex post sample values and the optimal portfolio is derived without mentioning the uncertainty inherent in these parameter values but the rational investor should take this uncertainty into account when forming expectations and probably will consider estimators that are less subject to estimation error than the classical sample mean this paper investigates alternative estimators of expected returns and their implications for the alleged gains from diversification an important observation is the crucial influence that errors in estimating expected returns have on portfolio analysis a closer examiprevious studies of international portfolio diversification have relied on ex post meanvariance analysis without considering the problem of estimation risk typically past averages are substituted for expected returns and no allowance is made for the uncertainty inherent in these parameter values first i demonstrate the shortcomings of such an approach and second i investigate another method of estimating expected returns initially proposed by stein by shrinking the sample averages toward a common mean i find that the out of sample performance of the optimal portfolio is substantially increased one of the implications of this method is that the classical conclusions vastly overestimate the possible gains in average returns instead benefits from diversification are more likely to accrue from a reduction in risk this paper draws on part of my dissertation at the university of chicago i am grateful to arnold zellner michael mussa george constantinides and especially john bilson for useful discussions and comments numerous improvements were also suggested by the referee this research received the generous financial support of the college interuniversitaire d etudes doctorales dans les sciences du management

markowitz s portfolio selection a fifty year retrospective this year marks the fiftieth anniversary of the publication of harry markowitz s landmark paper portfolio selection which appeared in the march 1952 issue of the journal of finance with the hindsight of many years we can see that this was the moment of the birth of modern financial economics although the baby had a healthy delivery it had to grow into its teenage years before a hint of its full promise became apparent what has always impressed me most about markowitz s 1952 paper is that it seemed to come out of nowhere compared to the work of his 1990 co nobel prize winners sharpe primarily for his paper on the capital asset pricing model and miller for his paper on capital structure markowitz s paper seems to have more of this flavor in 1676 sir isaac newton wrote his friend robert hooke if i have seen further it is by standing on the shoulders of giants newton 1959 and that is true of markowitz as well but like newton he certainly saw a long distance given the height of those shoulders markowitz was hardly the first to consider the desirability of diversification daniel bernoulli in his famous 1738 article about the st petersburg

portfolio constraints and the fundamental law of active management active portfolio management is typically conducted within constraints that do not allow managers to fully exploit their ability to forecast returns constraints on short positions and turnover for example are fairly common and materially restrictive other constraints such as market capitalization and value growth neutrality with respect to the benchmark or economic sector constraints can further restrict an active portfolio s composition we derive ex ante and ex post correlation relationships that facilitate the performance analysis of constrained portfolios the ex ante relationship is a generalized version of a previously developed fundamental law of active management and provides an important strategic perspective on the potential for active management to add value the ex post correlation relationship represents a practical decomposition of performance into the success of the return prediction process and the noise associated with portfolio constraints we verify the accuracy of these relati

robust multiobjective portfolio optimization a minimax regret approach abstract an efficient frontier in the typical portfolio selection problem provides an illustrative way to express the tradeoffs between return and risk following the basic ideas of modern portfolio theory as introduced by markowitz security returns are usually extracted from past data our purpose in this paper is to incorporate future returns scenarios in the investment decision process for representative points on the efficient frontier the minimax regret portfolio is calculated on the basis of the aforementioned scenarios these points correspond to specific weight combinations in this way the areas of the efficient frontier that are more robust than others are identified the underlying key contribution is related to the extension of the conventional minimax regret criterion formulation in multiobjective programming problems the validity of the approach is verified through an illustrative empirical testing application on the eurostoxx 50

efficiency wage models of unemployment keynesian economists hold it to be self evident that business cycles are characterized by involuntary unemployment but construction of a model of the cycle with involuntary unemployment faces the obvious difficulty of explaining why the labor market does not clear involuntarily unemployed people by definition want to work at less than the going wage rate why don t firms cut wages thereby increasing profits

some recent developments in labor economics and their implications for macroeconomics this paper reviews three recent directions of research on labor markets and the macroeconomy models of sectoral shifts and unemployment efficiency wage theories and insider outsider models of wage and employment determination sectoral shifts models show how permanent intersectoral shifts in labor demand and the slow process of labor reallocation across sectors may play an important role in explaining aggregate fluctuations efficiency wage and insider outsider models have in common the property that in equilibrium firms may pay wages in excess of market clearing these models provide potential explanations for persistent involuntary unemployment and segmented labor markets copyright 1988 by ohio state university press

worst case value at risk and robust portfolio optimization a conic programming approach classical formulations of the portfolio optimization problem such as mean variance or value at risk var approaches can result in a portfolio extremely sensitive to errors in the data such as mean and covariance matrix of the returns in this paper we propose a way to alleviate this problem in a tractable manner we assume that the distribution of returns is partially known in the sense that onlybounds on the mean and covariance matrix are available we define the worst case value at risk as the largest var attainable given the partial information on the returns distribution we consider the problem of computing and optimizing the worst case var and we show that these problems can be cast as semidefinite programs we extend our approach to various other partial information on the distribution including uncertainty in factor models support constraints and relative entropy information

signalling ability to pay and rent sharing dynamics abstract it is often argued that competitive and rent sharing models of wage determination should be distinguished by their long run properties in general rent sharing models predict the existence of a long run relationship between wages and firm specific ability to pay but the competitive model does not i present a two period counter example which demonstrates that rent sharing can be merely a short run phenomenon in the separating equilibria the firm signals ability to pay through first but not second period wage offers the model also has pooling equilibria in which the firm pays rents in the long run

diversifying portfolios of u s stocks with crude oil and natural gas a regime dependent optimization with several risk measures abstract we build a portfolio encompassing u s crude oil natural gas and stocks to study the diversification power of energy commodities such diversification power depends on the joint dependence structure of the three types of assets according to gatfaoui 2016a the dependence structure is time varying because individual asset returns exhibit several variance regimes we identify the corresponding regime specific multivariate copulas and incorporate them to well chosen risk measures specifically we minimize the portfolio s variance semi variance and tail risk in the presence and the absence of constraints on the portfolio s expected return and or stock investment first the return constraint reduces the performance of the optimal portfolio second the regime specific portfolio optimization implements an enhanced active management strategy over the whole sample period finally the tail risk optimal portfolio offers the most interesting risk return tradeoff however variance and semi variance optimal portfolios can also be considered in the absence of a return constraint

a model of the natural rate of unemployment since the publication of edmund phelps volume the new macroeconomics has treated the labor market as a dynamic process of rational search by unemployed workers for available vacancies wages are viewed as at least potentially flexible though free contracting between workers and firms may lead to fixed wages in the short run imperfect information is a crucial element of the theory for it implies both a need for contracting and a need for rational search rather than simple market clearing in each period a positive rate of frictional unemployment may exist in equilibrium denoted as the natural rate this unemployment is due to the frictions in the search process and imperfections in information rather than to any deficiency in aggregate demand milton friedman defined the natural rate as the level that would be ground out by the walrasian system of general equilibrium equations provided there is embedded in them the actual structural characteristics of the labor and commodity markets including market imperfections stochastic variability in demands and supplies the cost of gathering information about job vacancies and labor availabilities the costs of mobility and so on p 8 this paper reexamines the micro foundations of the natural rate in a model of labor market equilibrium in which turnover flows and imperfect information are explicitly considered workers may quit their current jobs to enter the unemployment pool in order to search among available vacancies for a more preferred position firms economize on turnover by an appropriate wage policy

empty promises and arbitrage analysis of absence of arbitrage normally ignores payoffs in states to which the agent assigns zero probability we extend the fundamental theorem of asset pricing to the case of no empty promises in which the agent cannot promise arbitrarily large payments in some states there is a superpositive pricing rule that can assign positive price to claims in zero probability states important to the market as well as assigning positive prices to claims in the states of positive probability with continuous information arrival no empty promises can be enforced by shutting down the agent s subsequent investments once wealth hits zero dogmatic disagreements create arbitrage opportunities in competitive markets that are sufficiently complete there may be someone in the economy who is certain correctly or not on objective grounds that gold prices will go up and someone else who believes there is a positive probability that gold prices will go down the first person will have an arbitrage opportunity if at the money put options on gold have a positive price while the second person will have an arbitrage opportunity if at the money put options on gold have a zero or negative price similarly if some people are sure their favorite sport teams or horses will win but others are not so sure any odds posted by a competitive bookmaker will imply arbitrage for one group or the other 1 in practice however dogmatic differences in beliefs do not imply actual arbitrage that can be used to generate arbitrarily large profits because people have limited resources and cannot make empty promises of payments that exceed their own ability to pay in states the market cares about even if those are states they personally believe to be impossible the purpose of this article is to extend the study of the absence of arbitrage to situations in which no empty promises are permitted

within firm human capital externalities in tunisia this case study exploits matched firm employee tunisian data in order to underline the role played by within firm human capital in worker remuneration the estimated returns to human capital in wage equations remain unchanged when the dummies representing firm heterogeneity are replaced in the list of regressors with three firm variables a textile industry dummy within firm mean education and firm age we find that part of what is usually considered as return to education may be due to within firm externalities

efficiency wages revisited the internal reference perspective the missing wage rigidity in general equilibrium models of e ciency wages is an artifact of the external wage reference perspective conventionally adopted by the literature e ciency wage models based on an internal perspective in which the wage reference is made dependent on the flrm s ability to pay are capable of generating strong wage rigidity this paper makes the point in the context of the gift exchange framework originally proposed by akerlof 1982 jel classiflcation e24 e32 j50

labor unions and the distribution of wages and employment in south africa few countries have higher wage inequality than south africa where wages of african and white workers differ by a factor of five using survey data collected in 1993 the authors analyze the complex effect of unions on this wage gap among male african workers in the bottom decile of the wage distribution union membership was associated with wages that were 145 higher than those of comparable nonunion workers and among those in the top decile the differential was 19 regression estimates also indicate that returns to observed productive characteristics of workers such as education and experience were larger for nonunion than union workers if the large union relative wage effect were cut in half the authors estimate that employment of african youth age 16 29 would increase by two percentage points and their labor force participation rate would also increase substantially

the dynamic black litterman approach to asset allocation abstract we generalize the black litterman bl portfolio management framework to incorporate time variation in the conditional distribution of returns in the asset allocation process we evaluate the performance of the dynamic bl model using both standard performance ratios as well as other measures that are designed to capture tail risk in the presence of non normally distributed asset returns we find that the dynamic bl model outperforms a range of different benchmarks moreover we show that the choice of volatility model has a considerable impact on the performance of the dynamic bl model

on the strategic behavior of large investors a mean variance portfolio approach abstract one key assumption of markowitz s model is that all traders act as price takers in this paper we extend this mean variance approach in a setting where large investors can move prices instead of having an individual optimization problem we find the investors nash equilibrium and redefine the efficient frontier in this new framework we also develop a simplified application of the general model with two assets and two investors to shed light on the potential strategic behavior of large and atomic investors our findings validate the claim that large investors enhance their portfolio performance in relation to perfect market conditions besides we show under which conditions atomic investors can benefit in relation to the standard setting even if they have not total influence on their eventual performance the two investors two assets setting allows us to quantify performance and do sensitivity analysis regarding investors market power risk tolerance and price elasticity of demand finally for a group of well known etfs we empirically show how price variations change depending on the volume traded we also explain how to set up and use our model with real market data

rent sharing before and after the wage bill many biases plague the analysis of whether employers share rents with their employees unlike what is predicted by the competitive labour market model using a portuguese matched employer employee panel this article is one of the first to address these biases in three complementary ways 1 controlling directly for the fact that firms that share more rents will ceteris paribus have lower net of wages profits 2 instrumenting profits via interactions between the exchange rate and the share of exports in firm s total sales 3 considering firm or firm worker spell fixed effects and highlighting the role of downward wage rigidity these approaches clarify conflicting findings in the literature and result in our preferred specifications in significant evidence of rent sharing a lester range of pay dispersion of 56 also shown to be robust to a number of competitive interpretations

a multisectorial matching model of unions abstract we develop an equilibrium matching model where unions have an important institutional presence monopolistic competition characterizes the goods market where only some sectors are unionized thus the model can vary the coverage of collective bargaining it can vary the degree of coordination between unions and alternatively consider national and sectorial unions calibration to the union premium implies a workers rent extraction parameter much lower than assumed in the matching literature we introduce unemployment insurance to study the interactions of policies with unions and find that unions only push for more generous benefits if this does not entail higher payroll taxes

asset allocation with correlation a composite trade off abstract we assess the ability of minimum variance portfolio allocation strategies accounting for time varying correlation between assets to provide performance benefits relative to an equally weighted portfolio prior to transaction costs correlation based strategies emphatically outperform the equally weighted benchmark this finding is strongest for short horizon correlation forecasts and attributed to dynamic correlation as opposed to variance forecasts thus estimation error is not found to be the primary obstacle to successful portfolio optimization rather frequent rebalancing and associated transaction costs pose a significant challenge limiting portfolio turnover through short selling restrictions and greater rebalancing error tolerance results in regular outperformance of the correlation based strategies even for large transaction costs taken together these findings provide evidence of a trade off between optimal portfolio performance forecasting horizon rebalancing frequency and transaction costs