multi product newsboy problem with limited capacity and outsourcing this paper considers a multi product newsboy system that produces multiple products for fulfilling independently uncertain demands which share the same production capacity to deal with possible shortage of limited capacity productions can be outsourced we consider two outsourcing strategies zero lead time outsourcing and nonzero lead time outsourcing the structural properties and solution procedures for the profit maximization models are developed numerical results are provided for obtaining some managerial insights

production capacity planning for multiple products under uncertain demand conditions abstract this study chiefly deliberates issues regarding capacity allocation for multiple products when producing multiple products a manufacturer needs to allocate a favorable production quantity to each product under conditions of uncertain demand since the excess or shortage of a product will in turn cause the loss of profit the proposed model and the corresponding algorithm in this study are used to find out the optimal capacity allocation under the given probability density function of specific demands and to effectively allocate limited capacity to multiple products with an aim to maximize profit finally the numerical example suggests that the marginal profit the inventory holding cost the shortage cost the loss of excess production and market demands should be considered in an effort to discover an optimal capacity allocation with regard to multiple products

adaptive ordering and pricing for perishable products we consider the combined problem of pricing and ordering for a perishable product with unknown demand distribution and censored demand observations resulting from lost sales faced by a monopolistic retailer we develop an adaptive pricing and ordering policy with the asymptotic property that the average realized profit per period converges with probability one to the optimal value under complete information on the distribution the pricing mechanism is modeled as a multiarmed bandit problem while the order quantity decision made after the price level is established is based on a stochastic approximation procedure with multiplicative updates

demographic effects on the natural rate of unemployment or baby booms and unemployment abstract this paper establishes the importance of demographics on both the actual rate and the natural rate of unemployment the actual dynamics can be quite complex and the natural rate is shown to depend crucially on population shifts

self enforcing contracts shirking and life cycle incentives he labor market is a rich and complicated place when a worker takes a job he expects to earn a wage but will also care about rates of wage growth fringe benefits levels of risk retirement practices pensions promotion and layoff rules seniority rights and grievance procedures in return the worker must give up some time but he is also asked to upgrade his skills train other workers provide effort and ideas and defer to authority in questions of how his time is spent great changes are occurring in the way labor market institutions such as these are modelled central to the new approach is the concept of a self enforcing implicit contract this is the latest in a series of variations on the ideas of azariadis 1975 baily 1974 and gordon 1974 and is one of the more exciting new developments in the theory of labor markets this essay will outline this approach and evaluate some of its accomplishments the ideas will be presented in the context of an incentive model that is of some independent interest the model was introduced by becker and stigler 1974 and was extended by lazear 1979 to account for wage growth and mandatory retirement in these papers the workers retire at a fixed age lending the name life cycle incentives to the approach more recently shapiro and stiglitz 1984 have used a version without a fixed retirement date to account for unemployment this version is often called the shirking model these models have generated some controversy but much of it can be resolved when the models are presented in the framework of self enforcing contracts in fact this simple incentive model can do even more it can provide a rationale for competitive hierarchies where firms place their workers in competition with

why do part time workers earn less the role of worker and job skills part time workers receive considerably lower hourly earnings than do full time workers using current population survey earnings files for september 1995 through december 2002 the author finds that measurable worker and job characteristics including occupational skill requirements account for much of the part time penalty longitudinal analysis of the data indicates that much of the remaining gap reflects worker heterogeneity evidenced by small wage gains and losses among workers switching between part time and full time jobs the lower skills of part time than full time workers result primarily from limited work experience and accumulation of human capital little evidence can be found of a large wage gap between part time and full time women a part time wage penalty is found for men but men account for less than one third of total part time employment

reducing the cost of demand uncertainty through accurate response to early sales traditionally fashion products have incurred high losses due to stockouts and inventory obsolence because long lead times coupled with a concentrated selling season force all or at least most production to be committed before demand information is available under a quick response system lead times are shortened sufficiently to allow a greater portion of production to be scheduled in response to initial demand we model and analyze the decisions required under quick response and give a method for estimating the demand probability distributions needed in our model we applied these procedures with a major fashion skiwear firm and found that cost relative to the current informal response system was reduced by enough to increase profits by 60 relative to the cost that would have been incurred if no response were used optimized response reduces cost by enough to roughly quadruple profits

observing bailout expectations during a total eclipse of the sun abstract the literature has not reached a consensus yet regarding the existence of sovereign creditor moral hazard exploiting an exceptional historical example this paper proposes an original method to address this issue as the corona which is observable only during a total eclipse of the sun market specific prices of repudiated bonds are observable only when extreme conditions segment the markets such very rare events allow for isolating pure country specific bailout expectations the paper shows that bailouts do create creditor moral hazard based on an impulse response analysis the econometric results further emphasize the influence of bailout expectations in sovereign bonds valuation

robust price setting newsvendor model with interval market size and consumer willingness to pay we consider a price setting newsvendor problem with partial information the newsvendor does not know the price dependent probability distribution of demand but is able to estimate lower and upper limits of the market size and consumer willingness to pay the objective is to minimize the maximum loss in expected profit or minimax regret we derive closed form expressions for optimal quantity and price and identify managerial insights

technical note robust newsvendor competition under asymmetric information we generalize analysis of competition among newsvendors to a setting in which competitors possess asymmetric information about future demand realizations and this information is limited to knowledge of the support of demand distribution in such a setting traditional expectation based optimization criteria are not adequate and therefore we focus on the alternative criterion used in the robust optimization literature the absolute regret minimization we show existence and derive closed form expressions for the robust optimization nash equilibrium solution for a game with an arbitrary number of players this solution allows us to gain insight into the nature of robust asymmetric newsvendor competition we show that the competitive solution in the presence of information asymmetry is an intuitive extension of the robust solution for the monopolistic newsvendor problem which allows us to distill the impact of both competition and information asymmetry in addition we show that contrary to the intuition a competing newsvendor does not necessarily benefit from having better information about its own demand distribution than its competitor has

wage offers and full time and part time employment by british women strong evidence in support of the hypothesis that women receive lower wage offers in part time jobs than in full time jobs is provided by estimation of wage offer functions for british women which control for self selection into these two types of jobs analysis of married women s employment decisions indicates that the difference in a woman s expected wage offers between full time and part time employment is an important determinant of whether she works full time while husband s income mainly affects the decision of whether to work in addition it appears that women who work despite having observed characteristics that discourage employment are much more likely to work part time

part time work wages and productivity evidence from belgian matched panel data the authors use matched employer employee panel data on belgian private sector firms to estimate the relationship between wage productivity differentials and the firm s labor composition in terms of part time work and gender findings suggest that the groups of women and part timers generate employer rents but also that the origin of these rents differs relatively lower wages for women relatively higher productivity for part timers interactions between gender and part time work suggest that the positive productivity effect is driven by male part timers working more than 25 hours whereas the share of female part timers is associated with wage penalties the authors conclude that men and women differ with respect to motives for reducing working hours and the types of part time jobs available to them women often have to accommodate domestic constraints by downgrading to more flexible jobs whereas male part time work is frequently related to training and collectively negotiated reductions in hours that

robust inventory management with stock out substitution abstract stock out substitution is a well documented phenomenon that occurs when customers seek a different product as a substitute for their first choice item if it runs out of stock we consider a single period inventory model with limited information regarding the external demands i e mean variance and covariance and focus on identifying the inventory levels that maximize the worst case expected profit we formulate a two stage optimization model the second stage characterizes the worst case joint demand distribution by treating the inventory levels as input parameters and the first stage identifies the optimal inventory levels based on the results of the second stage the closed form solution of the second stage problem is analytically intractable except for two special cases we develop closed form solutions for these two special cases and use them to develop a heuristic for the general case an extensive numerical study over a wide range of parameters indicates that the performance of the heuristic that we develop is nearly optimal we also provide insights into the effects of demand correlation substitution rate and other parameters on the optimal worst case expected profit of the system

divide the hours and conquer the surplus part time workers and pay abstract a theory is presented where the firm strategically over employs part time workers reductions in labor taxes increases in the worker s bargaining strength or reductions in their outside employment opportunities will all increase the level of part time work

does offshoring of materials and business services affect employment evidence from a small open economy the fear of massive job losses has prompted a fast growing literature on offshoring and its impact on employment in advanced economies this paper examines the situation for belgium it improves the offshoring intensity measure by computing a volume measure of the share of imported intermediates in output and it is among the first to address both materials and business services offshoring to high wage and low wage countries estimations of static and dynamic industry level labour demand equations augmented by offshoring intensities do not reveal a significant impact of either materials or business services offshoring on total employment for belgium between 1995 and 2003

seniority wages and productivity a turbulent decade why does a worker s wage tend to grow with seniority in the firm and what does this have to do with productivity two decades ago neoclassical labor economists thought that the theory of human capital provided a good answer to this question the last decade has however been one of puzzles and doubt at this point few would give an unambiguous answer and much hinges on the answer an attractive feature of human capital theory is that it yields a consistent and coherent explanation for several aspects of the employer employee relationship for example seniority systems layoff policies that vary with skill and the relationship between tenure and turnover can be explained in terms of human capital the fact that these explanations are connected leads however to something like a domino effect doubts about one cast doubt on the others if the human capital explanation for the wage seniority relationship is flawed then human capital explanations for other phenomena may require reevaluation in addition an important body of empirical research is built around the assumption that at any point in time a person s wage indicates the person s productivity included here is the extensive literature on the human capital earnings function as well as work on labor demand market discrimination and compensating differentials that assumption has become controversial in recent years in part because implicit contract theories predict that compensation will be redistributed over the period of the contract if a person s spot wage has little to do with spot productivity but rather is an instrument of a complex insurance or deferred compensation scheme then a reassessment of the empirical research may be necessary

family economics and macro behavior in this 1987 presidential address to the american economic association the author explores the contributions of the field of family economics to macroeconomic analysis the focus is on family behavior as an active endogenous factor that both affects and is affected by the evolution of the economy much of the time is spent on long term economic growth although i also discuss short and long cycles in economic activity and the interaction between overlapping generations through social security transmission of inequality and in other ways many conclusions in these and presumably other macro areas change radically when family choices get the attention they deserve excerpt

misalignment of productivity and wages across regions evidence from belgium abstractthis paper is one of the first to estimate how regions affect the productivity wage cost and cost competitiveness i e the productivity wage gap of firms detailed linked employer employee panel data for belgium and the hellerstein neumark framework are used to estimate dynamic models at the establishment level the findings show that interregional differences in productivity and wages are significant but to a large extent due to drivers at the individual and or firm level the research provides evidence that the specificity of the brussels region can be linked to its higher density compared with the rest of belgium robustness tests suggest that the relatively better ceteris paribus performance of firms in brussels is limited to the service sector

aggregate constrained inventory systems with independent multi product demand control practices and theoretical limitations in practice inventory managers are often confronted with a need to consider one or more aggregate constraints these aggregate constraints result from available workspace workforce maximum investment or target service level we consider independent multi item inventory problems with aggregate constraints and one of the following characteristics deterministic leadtime demand newsvendor basestock policy rq policy and ss policy we analyze some recent relevant references and investigate the considered versions of the problem the proposed model formulations and the algorithmic approaches finally we highlight the limitations from a practical viewpoint for these models and point out some possible direction for future improvements

robust multi item newsboy models with a budget constraint abstract in this paper we present robust newsboy models with uncertain demand the traditional approach to describing uncertainty is by means of probability density functions in this paper we present an alternative approach using deterministic optimization models we describe uncertainty using two types of demand scenarios namely interval and discrete scenarios for interval demand scenarios we only require a lower and an upper bound for the uncertain demand of each item while for discrete demand scenarios we require a set of likely demand outcomes for each item using the above scenarios to describe demand uncertainty we develop several minimax regret formulations for the multi item newsboy problem with a budget constraint for the problems involving interval demand scenarios we develop linear time optimal algorithms we show that the corresponding models with discrete demand scenarios are np hard and that they are solvable by dynamic programming finally we extend the above results to the case of mixed scenarios where the demand of some of the items is described by interval scenarios and the demand of the remaining items is described by discrete scenarios

does corporate social responsibility make over educated workers more productive this article provides first evidence on whether corporate social responsibility csr influences the productivity effects of over education by relying on detailed belgian linked employer employee panel data covering the period 1999 2010 our empirical results exhibit a positive and significant impact of over education on firm productivity moreover they suggest that the effect of over education is positively enhanced when the firm implements a csr process especially when it aims to have i a good match between job requirements and workers educational level ii a diverse workforce in terms of gender and age and iii a long term relationship with its workers when focussing on required education and over education the results suggest that csr besides representing an innovative and proactive approach for the firms stakeholders may also be beneficial for the firm itself through a bigger increase in productivity for each additional year of required education or over education

robust economic order quantity models abstract in this paper we study the classical economic order quantity eoq model under significant in particular the problem under consideration is the economic order quantity model with the input data of the demand rate the order cost and the holding cost rate being uncertain a robustness approach based on scenario characterization of the input data is adopted to describe the uncertainties the aim of the approach is to find an inventory policy that performs well under all realizable input data scenarios an efficient linear time algorithm is devised to find the robust decisions analytical results are obtained for the case where input data are defined in continuous intervals comparisons on performances between the robust decisions and the stochastic optimization decisions are conducted the results demonstrate the advantages of robustness approach