an econometric model of crowding out of lower education levels abstract unemployment in the netherlands has risen strongly in recent years there are large differences in unemployment rates between education levels according to neo classical theory these differences should be explained by distorted relative prices or by lack of human capital in this paper we test an alternative explanation according to this view the high unemployment rate for lower education levels is caused by excess labour supply highly educated people take the jobs which could be occupied by less educated people to test this view a regression model is developed estimation results indicate that differences in unemployment rates can indeed be explained by excess supply of qualified labour

the structure of unemployment we test for a unit root in postwar unemployment rates for sixteen oecd countries when a one time structural break is incorporated the unit root hypothesis can be rejected for most of the countries and the measured persistence of unemployment falls dramatically we then test for multiple structural changes and find evidence of one or two breaks for those countries for which the unit root hypothesis could be rejected almost all of the breaks are positive reflecting the sustained rise in european unemployment the major exception is the united states where long term unemployment rose in the 1970s and fell in the 1980s

new revelations about unemployment persistence in spain time series and panel data approaches using regional data this article aims to re examine the persistence of unemployment in spain for this purpose we use time series and cross section analysis from a time series viewpoint we disaggregate unemployment by regions and use unit root tests ar coefficients and fractional differencing parameters as indicators of persistence for the cross section approach we first estimate mean regressions of regional unemployment rates then using a panel of 114 periods and 50 provinces we estimate pooled fixed and random effects models finally following some recent developments we implement several panel data unit root tests previous studies had already shown the strong persistence of spanish unemployment our disaggregated analysis extends the finding to reveal that the persistence is greater in the most industrialized regions the results also suggest that a structural break took place in 1994 implying a decline in the unemployment persistence since then

noncooperative oligopoly in markets with a continuum of traders and a strongly connected set of commodities we show the existence of a cournot nash equilibrium for a mixed version of the shapley window model where large traders are represented as atoms and small traders are represented by an atomless part previous existence theorems for the shapley window model provided by sahi and yao 1989 in the case of economies with a finite number of traders and by busetto et al 2011 in the case of mixed exchange economies are essentially based on the assumption that there are at least two atoms with strictly positive endowments and indifference curves contained in the strict interior of the commodity space our result does not require this restriction it relies on the characteristics of the atomless part of the economy and exploits the fact that traders belonging to the atomless part have an endogenous walrasian behavior

comparative statics in a simple class of strategic market games this paper investigates the effects of entry in two sided markets where buyers and sellers act strategically applying new tools from supermodular optimization games sufficient conditions for different comparative statics results are obtained while normality of one good is sufficient for the equilibrium price to be increasing in the number of buyers normality of both goods is required for equilibrium bids and sellers equilibrium utilities to be increasing in the number of buyers when the economy is replicated normality of both goods and gross substitutes guarantee that the equilibrium of the strategic market game converges monotonically in quantities to the competitive equilibrium simple counter examples are provided to settle other potential conjectures of interest c 2007 elsevier inc all rights reserved

a strategic market game with complete markets abstract an exchange economy is modeled as a strategic market game with all pairwise markets available existence of noncooperative equilibria is proved it is shown that if resources are distributed in a skewed manner in equilibrium prices may not satisfy the no arbitrage condition one round of trade even with all goods serving as money is not sufficient to provide enough liquidity for efficient trade

trade fragmentation and coordination in strategic market games abstract this paper analyzes the incentives to trade and the validity of the law of one price in three strategic market games with multiple trading posts in bilateral oligopolies where traders have corner endowments in one commodity all agents participate in all the markets the law of one price holds in bilateral oligopolies and in the buy or sell market game where equilibrium strategies are locally unique when traders can simultaneously buy and sell on every market the law of one price fails and the set of equilibrium prices generically has the same dimension as the number of active markets journal of economic literature classification numbers d43 d51

wage aspirations and unemployment persistence abstract we use panel data to examine the empirical determinants of the reservation wage in particular the influence of previous wages and consider what this implies for the evolution of the natural rate of unemployment we find that previous wages have a significant but relatively small effect on reservation wages an elasticity between 0 15 and 0 47 we also find considerable differences across genders with previous wages being more important for men and market wages being more important for women overall our results suggest that the reservation wage will adjust quite quickly to shocks

a persistencia das flutuacoes no produto uma analise secular do crescimento economico brasileiro this paper analyzes the long memory properties of economic growth in brazil taking into consideration a series of annual data ranging from 1900 to 2008 we make use of arfima models as well as unit root tests with structural breaks the results show that both output and output per capita are highly persistent the trend cycle decomposition shows that the per capita gdp suffered stagnation in its long run trend in the beginning of the last century and in the 1980 s improving only in the 2000 s as for the gdp it shows a less erratic growth calling the attention the brazilian miracle period and the stagnation of the 1980 s

demographic differences in cyclical employment variation demographic differences in patterns of employment variation over the business cycle are examined in this paper three primary conclusions emerge first both participation and unemployment must be considered in any analysis of cyclical changes in the labor market second young people bear a disproportionate share of cyclical employment variation third failure to consider participation has led to undue pessimism about the effect of aggregate demand policy on high unemployment groups if participation did not surge reduction in overall unemployment to its 1969 level would reduce the unemployment of almost all demographic groups to very low levels

what have macroeconomists learned about business cycles from the study of seasonal cycles this paper argues that analysis of seasonal fluctuations can shed light on the nature of business cycle fluctuations the fundamental reason is that in many instances identifying restrictions about seasonal fluctuations are more believable than analogous restrictions about nonseasonal fluctuations the authors show that seasonal fluctuations provide good examples of preference shifts and synergistic equilibria they also find evidence against production smoothing and in favor of unmeasured variation in labor and capital utilization in some industries capacity constraints appear to bind copyright 1996 by mit press

endogenous strategic business cycles this paper examines an overlapping generations version of the shapley shubik market game we show existence of equilibria for the simple one commodity model and analyze the dynamics of the equilibrium trajectories generated in the model because of the non linearities generated by strategic interaction of agents in the model we find that complex and chaotic equilibrium dynamics are possible in this model for a much broader range of preferences than those for which grandmont econometrica53 no 5 1995 995 1045 found complicated dynamics in the perfectly competitive version of this model these results then provide an alternative to the usual technology based explanation for the historical fact that business cycles became an important economic phenomenon only with the onset of industrialization journal of economic literatureclassification numbers c72 c73 d51 l16

stable trading structures in bilateral oligopolies abstract this paper analyzes the formation of trading groups in a bilateral market where agents trade according to a shapley shubik j polit econ 85 1977 937 968 trading mechanism the only strongly stable trading structure is the grand coalition where all agents trade on the same market other weakly stable trading structures exist and are characterized by an ordering property trading groups can be ranked by size and cannot contain very different numbers of traders of the two types journal of economic literatureclassification numbers d43 d51

the returns to mobility and job search by gender using data from the national longitudinal survey of youth the authors estimate the returns to job search mobility and the interaction of search and mobility for young men and women they find st

measuring the gender disparities in unemployment dynamics during the recession evidence from portugal abstractthis article researches gender differences in the incidence and persistence of unemployment during the debt crisis and recession in portugal through estimating a dynamic random effects prob

the role of shocks and institutions in the rise of european unemployment the aggregate evidence two key facts about european unemployment must be explained the rise in unemployment since the 1960s and the heterogeneity of individual country experiences while adverse shocks can potentially explain much of the rise in unemployment there is insufficient heterogeneity in these shocks to explain cross country differences alternatively while explanations focusing on labour market institutions explain current heterogeneity well many of these institutions pre date the rise in unemployment based on a panel of institutions and shocks for 20 oecd nations since 1960 we find that the interaction between shocks and institutions is crucial to explaining both stylised facts

unemployment rate dynamics and persistent unemployment under rational expectations this paper develops a model of unemployment rate dynamics that provides an explanation of persistent cyclical unemployment that does not involve persistent expectational errors or other nonoptimizing behavior our results are based on the interaction of search dynamics and inventory adjustments an important element in these dynamics appears to be heterogeneity in the labor force which can be characterized as consisting of a relatively small group of high turnover individuals who comprise the bulk of normal unemployment and a larger group of low turnover individuals who dominate movements in cyclical unemployment our empirical results provide support for this theory as we demonstrate that the appropriately measured probability of becoming employed during a recovery falls relative to normal because of the unusually high proportion of low turnover individuals who have lost permanent jobs as aresult recovery is much slower than is indicated by normal relationships although each individual is searching optimally this abstract was borrowed from another version of this item

the strategic marshallian cross we prove existence and uniqueness of non autarkic equilibria in bilateral oligopoly assuming only that preferences are binormal and satisfy a weakened version of gross substitutes we permit complete heterogeneity of preferences and our analysis exploits the fact that payoffs depend only on own strategy and two universal aggregates this allows us to define strategic versions of supply and demand curves such that non autarkic nash equilibria are in 1 1 correspondence with intersections of these curves the same approach can be used to establish comparative statics under the assumptions above as examples we focus on adding players and changing endowments this competitive approach also allows us to conclude that much of conventional marshallian analysis is robust to strategic manipulation strategic marshallian cross strategic manipulation imperfect competition

atomic cournotian traders may be walrasian in a bilateral oligopoly with large traders represented as atoms and small traders represented by an atomless part when is there a nonempty intersection between the sets of walras and cournot nash allocations using a two commodity version of the shapley window model we show that a necessary and sufficient condition for a cournot nash allocation to be a walras allocation is that all atoms demand a null amount of one of the two commodities we provide four examples which show that this characterization holds non vacuously when our condition fails to hold we also confirm through some examples the result obtained by okuno et al 1980 small traders always have a negligible influence on prices while the large traders keep their strategic power even when their behavior turns out to be walrasian in the cooperative framework considered by gabszewicz and mertens 1971 and shitovitz 1973

the nature of occupational unemployment rates in the united states hysteresis or structural this article provides new evidence on the nature of occupational differences in unemployment dynamics which is relevant for the debate between the structural or hysteresis hypotheses we develop a procedure that permits us to test for the presence of a structural break at unknown date our approach allows the investigation of a broader range of persistence than the 0 1 paradigm about the order of integration usually implemented for testing the hypothesis of hysteresis in occupational unemployment in almost all occupations we find support for both the structuralist and the hysteresis hypotheses but stress the importance of estimating the degree of persistence of seasonal shocks along with the degree of long run persistence on raw data without applying seasonal filters indeed hysteresis appears to be underestimated when data are initially adjusted using traditional seasonal filters

strategic complements and substitutes in bilateral oligopolies this note analyzes the effect of product complementarity in a bilateral oligopoly we show that offers of traders on the two sides of the market are strategic complements substitutes if and only if the two goods are substitutes complements the outcome of the bilateral oligopoly game converges monotonically to the competitive equilibrium as the elasticity of substitution between the goods decreases to minus infinite

behind this structural boom the role of asset valuations we are in the midst of a structural boom the force of which has not been seen in this country since the 1920 s after the u s unemployment rate hit 6 percent in late 1994 following its two year recovery many experts assumed that unemployment had regained its naturalrate path the natural unemployment rate in the second half of the 1980 s had been put at around 6 5 percent in several estimates and if the trend reduction in the natural rate brought about by the continuing relative decline of high school dropouts in the labor force and those whose education stopped at the diploma is placed at 0 07 per annum it would have declined on that account to around 6 percent by 1995 phelps and gylfi zoega 1997 furthermore we saw in 1995 the end of

the economics of online postsecondary education moocs nonselective education and highly selective education abstract i consider economically sustainable online postsecondary education including massive open online courses moocs the analysis suggests that moocs will be financially sustainable substitutes for some non selective postsecondary education but there are substantial risks the analysis suggests that moocs will be financially sustainable substitutes for only a small share of highly selective postsecondary education hspe and are likely to collapse the economic model that allows hspe institutions to invest in advanced education and research i outline a non mooc model of online education that may allow hspe institutions to sustain their distinctive activities and to reach a larger number of students

on the power of dickey fuller tests against fractional alternatives abstract we examine the properties of dickey fuller unit root tests under fractionally integrated alternatives and find that these tests have quite low power

unit root tests persistence and the unemployment rate of the u s states author affiliation diego romero avila department of economics carretera de utrera km 1 pablo de olavide university 41013 seville spain dromtor upo escarlos usabiaga professor department of economics carretera de utrera km 1 pablo de olavide university 41013 seville spain cusaiba upo es corresponding author acknowledgment the authors would like to thank seminar participants at the pablo de olavide university and dg economics at the european central bank carlos usabiaga acknowledges the financial support from centro de estudios andaluces ecod1 05 033 special thanks go to junsoo lee and nikolay gospodinov for making available to us the codes to implement some of the techniques used in the paper and to two anonymous referees for suggestions that substantially improved the paper the usual disclaimer applies 1 introductionthe high persistence in unemployment rates observed in the developed world since the first oil shock has led to a vivid debate over which paradigm can better explain the behavior of unemployment rates the traditional strand of the literature that forms the basis of the natural rate theory phelps 1967 1968 friedman 1968 assumes that the unemployment rate evolves around an equilibrium level describing stationary fluctuations this equilibrium level or natural rate is set depending on fundamentals of the economy while initially the absence of theories explaining the determination of the natural rate meant that in practice it was taken to be constant and exogenous subsequent developments have attempted to identify the structural factors behind differences across economies and over time including labor productivity technological change real interest rates real exchange rates and energy prices to name a few see phelps 1994 phelps and zoega 1998 according to the structuralist view phelps 1994 most shocks to unemployment are temporary but occasionally the natural rate permanently changes and is affected by variations in the aforementioned structural factors as a consequence the unemployment rate may be characterized as a process that is stationary once a small number of structural breaks are allowed for in contrast to the natural rate and structuralist approaches the hysteresis hypothesis see blanchard and summers 1986 1987 implies that the unemployment rate is path dependent and temporary shocks can affect unemployment permanently 1 while hysteresis is thought to imply that the natural rate is conditioned by the level of unemployment recorded in the past persistence in unemployment which is a special case of the natural rate hypothesis entails a slow adjustment process of reversion toward the mean thus hysteresis implies that unemployment is characterized by a unit root while persistence is characterized by a near unit root in the latter case shocks to unemployment though long lasting would not have a permanent effect to discriminate among theories explaining the behavior of unemployment rates unit root tests have been widely applied the hysteresis hypothesis has been formulated as a unit root process and its rejection lends support to the natural rate hypothesis if no breaks are included in the specification and the structuralist hypothesis if breaks are allowed for the purpose of this article is to investigate which theoretical paradigm most closely represents the behavior of unemployment rates in the states of the united states over the period 1976 2004 we first apply the individual lagrange multiplier lm t statistic proposed by schmidt and phillips 1992 to monthly data and we fail to reject the null hypothesis of a unit root in unemployment for forty states perron 1989 pointed out that the presence of structural changes could favor the nonrejection of the unit root null if they are not properly accounted for therefore we employ the minimum lm t statistic allowing for up to two endogenous changes in level proposed by lee and strazicich 2003

unemployment questions and some answers in more or less every country in the oecd unemployment was lower in the decades following the second world war than in any other period of comparable length either before or since for example in britain unemployment has exceeded 5 in every peacetime decade from 1850 onwards except for the 1950s and 1960s alternatively as we can see in table 1 p 779 average unemployment in the 1980s and 90s is higher generally much higher than in the 1960s in every country considered why this is so is one of the questions which underlies this paper a second question which is also illustrated in the unemployment numbers presented in table 1 p 779 concerns the causes of the enormous variation in unemployment rates across the oecd countries as we shall see these are difficult questions the first in particular is one for which we do not have a complete answer by this i do not mean that we do not have theories which are broadly consistent with these numbers in fact we have theories consistent with more or less any numbers what we lack is a satisfactory empirical explanation of the time series pattern of oecd unemployment in what follows we remain focused on these two questions first considering the theoretical background and then looking at some possible answers we finish with some speculative conjectures on the first question

wage dynamics reconciling theory and evidence u s macroeconomic evidence shows a negative relation between the rate of change of wages and unemployment in contrast most theories of wage determination imply a negative relation between the level of wages and unemployment in this paper we ask whether one can reconcile the empirical evidence with theoretical wage relations we reach three main conclusions first we derive the condition under which the two can indeed be reconciled we show the constraints that such a condition imposes on the determinants of workers reservation wages as well as the relative importance of workers outside options as opposed to match specific productivity in wage determination second in the light of this condition we reinterpret the presence of an error correction term in macroeconomic wage relations for most european economies but not in the united states third we show that whether this condition holds or not has important implications for the effects of a number of variables from real interest rates to oil prices to payroll taxes on the natural rate of unemployment this abstract was borrowed from another version of this item

wage setting and unemployment persistence in europe japan and the usa the persistence of high unemployment in the main european economies is one of the most puzzling economic developments of the past fifteen years average japanese unemployment has risen slightly since the mid seventies whereas unemployment in the united states still exhibits cyclical fluctuations around a gently rising level in marked contrast average unemployment in france germany and the united kingdom rose to a higher plateau during the latter part of the seventies shot up again in the early eighties and has remained persistently high identification of the causes of such unemployment persistence is crucial before one makes policy recommendations three possible causes spring to mind first persistence in the determinants of equilibrium and disequilibrium unemployment second excessive power of insiders in wage setting combined with high correlation between employment status and insider status and finally a high degree of state dependence sluggishness in labour demand although in general one expects all three causes to have played a role in the persistence of high european unemployment there is still a need to identify their relative importance the first set of factors has been assessed empirically in recent papers by among others sachs 1983 bruno and sachs 19x5 bruno 1986 layard and nickel1 1985 bean layard and nickel1 1986 newell and symons 1985 and others many of these papers have also allowed for sluggishness in labour demand although they did not particularly focus on it the second set of factors has been investigated by blanchard and summers 1986 who concluded that there is evidence of much higher correlation between employment status and insider status in the three largest european economies than in the united states

the persistence of unemployment in the usa and europe in terms of fractionally arima models this article examines the persistence of unemployment in the usa and four european countries by means of fractionally integrated arma arfima models in doing so a type of flexibility in modelling low frequency dynamics not achieved by non fractionally arima models can be provided the results indicate that the unemployment series are much more persistent in some countries such as the uk and france than in others including germany or the usa

evidence on the dynamics of unemployment by gender we present empirical evidence regarding unemployment dynamics for women and men in eight oecd countries unit root tests are used to examine the unemployment dynamics of women and men failure to reject the unit root hypothesis is consistent with unemployment hysteresis rejection of the unit root hypothesis indicates that unemployment dynamics are best explained by the natural rate of unemployment or the structuralist view we find evidence of gender differences in unemployment dynamics in canada germany and the us but not in other countries while there are some differences in the extent of persistence across gender and across countries the degree of persistence for both female and male unemployment rates is fairly low in all countries our results therefore contrast with substantial empirical evidence of high levels of unemployment persistence in european countries

hysteresis and instability in the natural rate of unemployment in this paper it is pointed out that the long run phillips curve genus contains upward and downward sloping species as well as the vertical species two models are used in one the rate of inflation helps determine the natural rate of unemployment as proposed by friedman in the other the process of moving from one inflation rate to another helps shape the natural rate according to the hysteresis effect proposed by phelps in both cases the resulting models are unstable implying that a vertical long run phillips curve will not be regained if disturbed

on the periodic structure of the business cycle this article tests whether an economic recovery is equally likely to occur in any month of the year i test this hypothesis with a homogeneous markov switching regime model and use the turning point dates for business cycles marked by the national bureau of economic research and romer i tend to find unequal probabilities to switch from recession to expansions in particular the spring and the month of december appear to have higher incidence of economic recovery my results also imply that recessions and expansions are on average longer or shorter depending on what time of the year they start this suggests the presence of a seasonal pattern in business cycle durations though such a notion of seasonality is quite different from the common one based on unobserved component linear time series models i investigate issues that go beyond linear dependence between seasonality and business cycles

the business cycle effects of christmas abstract why do countries and industries with large seasonal fluctuations also have large business cycles it is well known that seasonal fluctuations account for the bulk of total output fluctuations yet it is unknown whether seasonal fluctuations can trigger business cycles using a procedure that allows for identification of seasonal innovations i found that seasonal shocks explain 50 of the business cycle in aggregate output such findings provide a novel and powerful explanation for the observed strong correlation between seasonal fluctuations and business cycles the implication is that in addition to trying to determine whether it is monetary technology or other types of shocks that cause business cycles we should be looking at what causes seasonality

oecd unemployment structural breaks and stationarity the paper is concerned with testing the unemployment rate of twenty two oecd countries for stationarity a sequential testing procedure was applied where the break data is endogenized three different models were tested for unit roots it was found that the crash model which allows for a shift in the level of the unemployment rate was most relevant furthermore most breaks were associated with the first oil price shock results suggest that in nine countries the unit root can be rejected in ten countries the null hypothesis cannot be rejected and in three cases the results suggest possible trend stationarity

cointegration fractional cointegration and exchange rate dynamics multivariate tests due to johansen 1988 1991 as implemented by baillie and bollerslev 1989a and diebold gardeazabal and yilmaz 1994 reveal mixed evidence on whether a group of exchange rates are cointegrated further analysis of the deviations from the cointegrating relationship suggests that it possesses long memory and may possibly be well described as a fractionally integrated process hence the influence of shocks to the equilibrium exchange rates may only vanish at very long horizons in the article by baillie and bollerslev 1989a it is argued that seven different nominal spot and forward exchange rates all contain unit roots in their univariate time series representations at the same time however the spot exchange rates appear to be tied together in the long run through a cointegration type relationship the latter finding of baillie and bollerslev has attracted particular interest and several studies such as those by hakkio and rush 1991 and sephton and larsen 1991 have already addressed this issue using the same data as the baillie and bollerslev article sephton and larsen 1991 describe the evidence for the presence of cointegration as being fragile and note that mixed conclusions are reached by truncating the baillie and bollerslev sample at different points in time diebold gardeazabal and yilmaz 1994 henceforth diebold et al provide interesting evidence that application of the johansen 1988 1991 tests with and without an intercept will result in different inferences on the baillie and bollerslev data set furthermore diebold et al carry out an ex ante forecasting experiment and find that the addition of an error correction term to the martingale model as implied by the standard cointegration paradigm fails to reduce the prediction mean square error when compared to a simple martingale model this therefore leads diebold et al to conclude that there exists substantial uncertainty regarding the existence of cointegration relationships among nominal dollar exchange rates this article provides some additional evidence on the existence of such a long run relationship among the same seven nominal spot exchange rates after further analysis it appears that a form of cointegration does exist between the exchange rates so that they do not drift apart in the long run we argue that this form of cointegration is

noncooperative oligopoly in economies with infinitely many commodities and traders in this paper we extend the noncooperative analysis of multilateral oligopoly to exchange economies with infinitely many commodities and trader types where exchange is modelled using a strategic market game with commodity money and trading posts we prove the existence of an active cournot nash equilibrium and its convergence to a walras equilibrium when the economy is replicated

nice trivial equilibria in strategic market games an example of an exchange economy is provided satisfying all of the assumptions of dubey and shubik 1978 for which the trivial nash equilibrium is the unique equilibrium point of the associated market game from this example we are led to propose an argument related to the intensity of competition explaining whv there could be no trade at an equilibrium point c 1998 academic press

estimating persistence in canadian unemployment evidence from a bayesian arfima the degree of persistence in aggregate canadian unemployment is estimated within a bayesian arfima class of models the results conclude that unemployment exhibits persistence in the short and intermediate run the evidence of persistence is stronger than previously reported by koustas and veloce 1996 this persistence cast a vital implication regarding disinflation policies based on the unemployment rate these policies will prove very costly in terms of lost output and if implemented they considerably lengthen recessions

the value of postsecondary credentials in the labor market an experimental study we study employers perceptions of the value of postsecondary degrees using a field experiment we randomly assign the sector and selectivity of institutions to fictitious resumes and apply to real vacancy postings for business and health jobs on a large online job board we find that a business bachelor s degree from a for profit online institution is 22 percent less likely to receive a callback than one from a nonselective public institution in applications to health jobs we find that for profit credentials receive fewer callbacks unless the job requires an external quality indicator such as an occupational license jel i23 i26 j24 j44 j63 m51

can online learning bend the higher education cost curve we examine whether online learning technologies have led to lower prices in higher education using data from the integrated postsecondary education data system we show that online education is concentrated in large for profit chains and less selective public institutions we find that colleges with a higher share of online students charge lower tuition prices we present evidence of declining real and relative prices for full time undergraduate online education from 2006 to 2013 although the pattern of results suggests some hope that online technology can bend the cost curve in higher education the impact of online learning on education quality remains uncertain

atomic leontievian cournotian traders are always walrasian abstract we consider a bilateral oligopoly version of the shapley window model with large traders represented as atoms and small traders represented by an atomless part for this model we show that when atoms have leontievian utility functions any cournot nash allocation is a walras allocation and consequently it is pareto optimal

structural breaks and fractional integration in the us output and unemployment rate abstract in this article we examine the presence of structural breaks in the us output and unemployment rate by means of using fractionally integrated techniques the results based on robinson s journal of the american statistical association 89 1994 1420 tests indicate that for unemployment the inclusion of breaks does not affect to the degree of integration of the series while for the gnp we observe a reduction in its order of integration of about 0 25 when a break due to the oil price crisis is taken into account

liquid markets and competition abstract a market is liquid if no individual s actions have a big effect on the prices of goods traded in that market perfectly competitive markets are therefore perfectly liquid it is well known that market liquidity can be achieved by increasing the number of traders so that individual trades are small compared to total trades we show that even when there are only few traders market liquidity can be achieved through large short sales in which net trades are small relative to gross trades in particular for a natural variant of the market game which permits unlimited short sales we show that there is always a nash equilibrium allocation arbitrarily close to a competitive equilibrium allocation of course not all ne are near competitive only the large short sales ne are nearly liquid and hence close to ce