revisited are shocks to energy consumption permanent or temporary new evidence from a panel suradf approach abstract this paper explores whether the hypothesis of energy consumption stationarity is supported in different regions the stationarity properties indicate that the impact of a reduction in energy consumption or a realignment policy is only temporary and over time the series will revert back to the trend path this paper first applies the panel seemingly unrelated regressions augmented dickey fuller panel suradf test developed by breuer et al breuer j b mcnown r wallace m s 2001 misleading inferences from panel unit root tests with an illustration from purchasing power parity review of international economics 9 3 482 493 which allows us to account for possible cross sectional effects and to identify how many and which members of the panel contain a unit root the main conclusion is that the stationarity of energy consumption will be affected by the differences among the five regions made up of 84 countries during the period 1971 2003 similar conclusions are reached when we analyze country groups based on levels of development moreover the results reveal that conventional panel unit root tests can lead to misleading inferences which are biased towards stationarity even if only one series in the panel is strongly stationary lastly some policy implications emerge from our results

disaggregate energy consumption employment and income in turkey the purpose of this paper is to contribute to literature on energy consumption and economic growth relationship by examining how much of the variance in national income growth can be explained by the growth of different sources of energy consumption and employment in turkey we use the recently developed generalized forecast error variance decomposition technique of koop et al j econom 74 1996 119 and pesaran and shin econ lett 58 1998 17 to determine the information content of the growth rate of energy consumption waste seems to have the largest initial impact followed by oil however over a 3 year horizon lignite appears to explain the largest forecast error variance of gdp the total energy consumption explains 21 of forecast error variance of gdp energy consumption appears to be almost as important as employment in turkey therefore policy makers may be interested in identifying the energy dependencies of economic growth in allocating the energy investment budget

stochastic divergence or convergence of per capita carbon dioxide emissions re examining the evidence this paper revisits the time series literature on the convergence of per capita carbon dioxide co2 emissions and examines the robustness of previous results using a sample of oecd countries for the period 1950 2002 we employ a battery of stationarity and unit root tests including those that allow for cross sectional dependencies within the panel we also correct for inaccuracies in previous studies that could result in a trend stationary series being labelled as converging even if it were actually diverging from the international average the body of evidence provided by our analysis suggests that per capita co2 emissions have not converged among oecd countries during the period under consideration this finding is of importance to both climate change policy makers and to those who construct climate change models

mutual fund incubation and the role of the securities and exchange commission a mutual fund family incubates a fund when it creates a privately subsidized fund not available to the general investing public it destroys unsuccessful incubator funds the few successful funds will report higher incubation returns than the market return in advertisements intended to attract money from individual investors this practice is currently allowed by the sec the evidence is that incubation returns are not a good predictor of subsequent fund performance and likely serve to mislead unsuspecting investors

oil and the macroeconomy since world war ii all but one of the u s recessions since world war ii have been preceded typically with a lag of around three fourths of a year by a dramatic increase in the price of crude petroleum this does not mean that oil shocks caused these recessions evidence is presented however that even over the period 1948 72 this correlation is statistically significant and nonspurious supporting the proposition that oil shocks were a contributing factor in at least some of the u s recessions prior to 1972 by extension energy price increases may account for much of post opec macroeconomic performance

stochastic convergence in per capita energy consumption and its catch up rate evidence from 26 african countries using annual data from 1971 to 2014 we examine stochastic conditional convergence in per capita energy consumption for 26 low income lower middle income and upper middle income african countries

convergence analysis of regional energy efficiency in china based on large dimensional panel data model abstract with the advent of the era of big data large dimensional spatial panel data is gradually used to do empirical research in the macroeconomic field this paper adopts a data envelopment analysis dea approach to calculate regional energy efficiency based on the perspective of total factor energy efficiency using statistical data of 30 administrative regions in china on basis of spatial effects the paper assesses the convergence of regional energy efficiency in china using large dimensional spatial panel data model our results indicate that 1 there is significant spatial autocorrelation and clear spatial effects in china s regional energy efficiency thus spatial effects should not be ignored when assessing the convergence of regional energy efficiency in china 2 during the period from 2000 to 2014 china s regional energy efficiency not only exhibits absolute convergence but also exhibits conditional convergence the convergence rate is higher than the rate of absolute convergence after controlling for the initial conditions of the level of economic development foreign direct investment and government influence 3 the convergence rate of china s regional energy efficiency from 2004 to 2014 is higher than the convergence rate for the period of 2000 2004 which indicates that industry transfer has contributed to improvement in the convergence of regional energy efficiency in china since 2004

professionally managed publicly traded commodity funds investment in professionally managed publicly traded commodity funds has grown rapidly in recent years this is the first comprehensive study of the performance of these funds it is found that randomly selected funds offer neither an attractive alternative to bonds nor a profitable addition to a portfolio of stocks and bonds furthermore past performance of these funds offers very little information about future performance the findings may be explained by the large transactions costs incurred by these funds and their primary reliance on technical analysis copyright 1987 by the university of chicago

is there convergence in per capita renewable energy consumption across u s states evidence from lm and rals lm unit root tests with breaks abstract given the federal and state policy initiatives to curb fossil fuel consumption and expand the use of renewable energy sources in the u s this study investigates the convergence properties of per capita renewable energy consumption across u s states including the district of columbia in addition to cross sectional tests of and convergence our study employs lm and rals lm unit root tests with endogenously determined structural breaks to test for stochastic convergence traditional cross sectional tests indicate that both and convergence of per capita renewable energy consumption exists across u s states moreover our results also provides clear support for stochastic convergence of per capita renewable energy consumption for a majority of u s states including the district of columbia once allowance is made for structural breaks

stochastic convergence in per capita co2 emissions evidence from emerging economies 1921 2014 abstract we employ the recently developed lm and rals lm unit root tests that allow for endogenously determined structural breaks to study stochastic convergence in relative per capita co2 emissions over the period 1921 to 2014 for a balanced panel of emerging market economies the results provide mixed evidence of the presence of stochastic convergence in particular stochastic convergence is achieved for eleven out of the seventeen countries under investigation this implies that the energy regulatory framework in these countries needs to be revaluated in order to reduce the carbon footprint to further comprehend the factors behind the observed disparities in emission stability we analyse the determinants of the identified groups an examination of the determinants of the observed behaviour in relative per capita co2 emissions reveal that income population financial development and trade are significant drivers with trade predominantly playing a larger role in emission growth also weak evidence is found in terms of a catching up effect in the growth of relative per capita co2 emissions

long memory and disaggregated energy consumption evidence from fossils coal and electricity retail in the u s abstract in this paper the long memory properties of disaggregated fossils coal and electricity retail consumption in the u s over the 1989 2009 period are examined the presence of long memory is related to autocorrelation persistence of each series our results show that there is heterogeneity in the order of integration between these types of energy consumption and for the different sectors employed which is affected by the inclusion of a break event the order of integration was generally higher for the case of a break in the intercept than in the slope with the latter being more plausible for all series

conditional convergence in us disaggregated petroleum consumption at the sector level abstractwe test for convergence in disaggregated petroleum consumption at the sector level for the united states using the recently proposed garch unit root test suitable for high frequency data we find evidence of convergence for just over half of the series including total petroleum consumption in each sector and approximately three quarters of the disaggregated petroleum consumption series in transportation

price of oil and world inflation and recession new evidence shows that the commonly held assumption that the 1973 74 oil price increase directly affected us and world inflation and subsequent recession is consistent with the empirical data an extended lucas varro real income equation applied to the us united kingdom canada france germany italy japan and the netherlands gives mixed results partly because of price control and decontrol programs simulation experiments on the price control variable using us data finds strong effects further studies can be made when consistent international data is available for the 1979 80 period 18 references 4 figures 3 tables dck

are shocks to energy consumption permanent or temporary evidence from 182 countries this article applies univariate and panel data unit root tests to annual panel data for 182 countries over the period 1979 2000 to examine the stationarity properties of per capita energy consumption the univariate unit root test can only reject the unit root null for 56 countries or 31 of the sample at the 10 level or better however univariate unit root tests have low power with short spans of data and therefore failure to reject the unit root null should be treated with caution when we apply the panel data unit root test we find overwhelming evidence that energy consumption is stationary we discuss the policy implications of these findings and offer suggestions for future research

fourier quantile unit root test for the integrational properties of clean energy consumption in emerging economies abstract since the adoption of the kyoto protocol in 1997 and its entry into force in 2005 as well its aftermath such as the doha amendment and paris agreement national policies have become more conscious of the usage of clean energy mostly the different forms of renewable energy and nuclear energy ratifying countries and signatories had committed themselves to binding targets for the reduction of greenhouse emissions by 8 with respect to 1990 levels until 2012 also based on the particular contribution to global emissions from each country this paper examines the integrational properties of clean energy consumption from eight emerging economies which are also high greenhouse gas emitters the empirical results show that the clean energy consumption is stationarity for brazil and philippines by using a quantile unit root test without smooth breaks koenker and xiao 2004 however after capturing the smooth breaks bahmani oskooee et al 2018 we find the clean energy consumption of china pakistan and thailand are stationary the time varying deterministic trend with smooth breaks is more fitted to the path of clean energy consumption in comparison to the deterministic trend without smooth breaks the paper suggests economic insights useful for policy making

the employment and wage effects of oil price changes a sectoral analysis in this paper we use micro panel data to examine the effects of oil price changes on employment and real wages at the aggregate and industry levels we also measure differences in the employment and wage responses for workers differentiated on the basis of skill level we find that oil price increases result in a substantial decline in real wages for all workers but raise the relative wage of skilled workers the use of panel data econometric techniques to control for unobserved heterogeneity is essential to uncover this result which is completely hidden in ols estimates while the short run effect of an oil price increase on aggregate employment is negative the long run effect is in fact positive we find that changes in oil prices induce changes in employment shares and relative wages across industries however we find little evidence that oil price changes cause labor to consistently flow into those sectors with relative wage increases copyright 1996 by mit press

a literature survey on energy growth nexus abstract this paper provides a survey of the recent progress in the literature of energy consumption economic growth and electricity consumption economic growth causality nexus the survey highlights that most empirical studies focus on either testing the role of energy electricity in stimulating economic growth or examining the direction of causality between these two variables although the positive role of energy on growth has become a stylized fact there are some methodological reservations about the results from these empirical studies a general observation from these studies is that the literature produced conflicting results and there is no consensus neither on the existence nor on the direction of causality between energy consumption electricity consumption and economic growth as a policy implication to avoid from conflicting and unreliable results the authors may use the autoregressive distributed lags bounds test two regime threshold co integration models panel data approach and multivariate models including new variables such as real gross fixed capital formation labor force carbon dioxide emissions population exchange rates interest rates etc thus the authors should focus more on the new approaches and perspectives rather than by employing usual methods based on a set of common variables for different countries and different intervals of time

structural breaks and petroleum consumption in us states are shocks transitory or permanent abstract this short communication extends the literature on the stationarity of energy consumption to the case of us petroleum consumption at the state level from 1960 to 2007 the results of lee and strazicich 2003 and narayan and popp forthcoming unit root tests with endogenously determined structural breaks in the intercept and slope of the trend function reveal break dates that correspond to the two opec oil shocks of the 1970s along with the double dip recession of 1980 1982 the null hypothesis of a unit root in petroleum consumption is rejected for a majority of states these results highlight the importance of recognizing the heterogeneity in the behavior of petroleum consumption across states in the formulation of energy conservation and demand management policies

structural breaks and energy efficiency in fiji this paper examines how energy output ratios eyrs in fiji have responded to the major energy crises and in particular if these ratios have declined after the energy shocks the expectation is that energy efficiency should improve after an energy crisis for this purpose we have used at first a few simpler procedures and then a recently developed more powerful tests for structural breaks by bai and perron bai j perron p 1998 estimating and testing linear models with multiple structural changes econometrica 66 47 78 bai j perron p 2003a computation and analysis of multiple structural change models journal of applied econometrics 18 1 22 bai j perron p 2003b critical values for multiple structural change tests econometrics journal 6 72 78 policy implications of our results are discussed

stochastic convergence in per capita fossil fuel consumption in u s states abstract this study examines the stochastic convergence of per capita fossil fuel consumption across u s states including the district of columbia utilizing lm and rals lm unit root tests with allowance for endogenously determined structural breaks our results indicate that with the exception of nevada the evidence from two break and one break lm and rals lm unit root tests rejects the null hypothesis of a unit root in the relative per capita fossil fuel consumption in the u s this finding indicates the presence of stochastic convergence in relative per capita fossil fuel consumption in the u s states

conditional convergence in australia s energy consumption at the sector level abstract we examine the convergence of energy consumption per capita at the sector level in australia over the period 1973 74 to 2013 14 to do so we employ recently developed lm and rals lm unit root tests that accommodate up to two endogenously determined structural breaks we find support for energy consumption per capita convergence for six of seven sectors in australia

nonlinear globalization threshold effect of energy intensity convergence in belt and road countries abstract this paper investigates the role of globalization especially so called threshold effect in convergence of energy intensity along the belt and road countries during the period 1992 2016 different from the previous studies which primarily consider the linear effect and neglect the cross sectional dependence of convergences we construct a panel smooth transition regression model in this work simultaneously taking dynamics heterogeneity non linear and cross sectional dependence characteristics into account the results show that there exists a non linear globalization threshold effect on the unconditional beta convergence conditional beta convergence and club convergence of energy intensity and the convergence becomes faster when the globalization level is above the threshold these findings imply that a rise in the level of globalization contributes to the convergence of energy intensity in the belt and road countries thus governments in such countries could reduce energy intensity through increasing the level of globalization which may in turn be achieved by deep cross national cooperation in economic social and political areas

energy consumption and gdp causality relationship in g 7 countries and emerging markets abstract the causality relationship between energy consumption and income is a well studied topic in energy economics this paper studies the time series properties of energy consumption and gdp and reexamines the causality relationship between the two series in the top 10 emerging markets excluding china due to lack of data and g 7 countries we discover bi directional causality in argentina causality running from gdp to energy consumption in italy and korea and from energy consumption to gdp in turkey france germany and japan hence energy conservation may harm economic growth in the last four countries

are fluctuations in coal consumption per capita temporary evidence from developed and developing economies abstract this paper investigates the unit root properties of coal consumption per capita for the 47 developed and developing countries for 1965 2010 period to examine the stationary properties of coal consumption per capita lagrange multiplier lm unit root test with one break and two breaks crash model has been utilized according to empirical results the coal consumption is stationary in almost all the countries analyzed thus if the coal consumption is mean or trend reverting then it follows that the series will return to its mean value or trend path and it might be possible to forecast future movements in the coal consumption based on past behaviors of the series for the policy makers it is not necessary to pay attention to coal consumption excepting for indian and italian however for the researchers it is important to take into account the stationarity property of coal consumption and also structural breaks should be modeled in their future studies

joint inventory and pricing decisions for an assortment we seek optimal inventory levels and prices of multiple products in a given assortment in a newsvendor model single period stochastic demand under price based substitution but not stockout based substitution we address a demand model involving multiplicative uncertainty motivated by market share models often used in marketing the pricing problem that arises is known not to be well behaved in the sense that in its deterministic version the objective function is not jointly quasi concave in prices however we find that the objective function is still reasonably well behaved in the sense that there is a unique solution to the first order conditions and this solution is optimal for our problem

oil prices inflation and interest rates in a structural cointegrated var model for the g 7 countries sharp increases in the price of oil are generally seen as a major contributor to business cycle asymmetries moreover the very recent highs registered in the world oil market are causing concern about possible slowdowns in the economic performance of the most developed countries in this paper a structural cointegrated var model has been considered for the g 7 countries in order to study the direct effects of oil price shocks on output and prices and the reaction of monetary variables to external shocks our results can be summarized as follows i a stationary money demand as suggested by the classic theory of money can be identified for most countries ii according to the estimated coefficients of the structural part of the model for all countries except japan and u k the null hypothesis of an influence of oil prices on the inflation rate cannot be rejected inflation rate shocks are transmitted to the real economy by increasing interest rates iii impulse response analysis suggests for most countries the existence of an instantaneous temporary effect of oil price innovations on prices iv impulse response functions indicate different monetary policy reactions to inflationary and growth shocks v the simulation exercises directed to estimate the total impact of the 1990 oil price shock indicate that for some countries u s a significant part of the effects of the oil price shock is due to the monetary policy reaction function for other countries canada france and italy however the total impact is offset at least in part by an easing of monetary conditions

convergence in per capita energy use among oecd countries abstract unlike previous studies which mainly focus on the integration properties of energy consumption and production this study examines the convergence of per capita energy use among 25 oecd countries over the period 1960 to 2010 in particular newly developed lm and rals lm unit root tests with allowance for two endogenously determined structural breaks are employed the results indicate significant support for per capita energy use convergence among oecd countries

a club convergence analysis of per capita energy consumption across australian regions and sectors we examine convergence in per capita energy consumption across nine sectors and seven states and territories in australia over the period 19902016 using the phillips sul club convergence approach we find evidence of multiple convergence clubs for aggregate energy consumption per capita and for energy consumption per capita in eight of the nine sectors with full club convergence in the case of electricity the presence of multiple equilibria for most sectors reflect that states with similar features in terms of climate economic activities and population size among others tend to exhibit similar energy consumption patterns our results highlight the need to tailor policies designed to reduce energy consumption in specific sectors to the consumption convergence paths unique to particular clusters of states

is per capita electricity consumption stationary time series evidence from oecd countries this study examines the stationary properties of per capita electricity consumption in which the endogenously determined break points are incorporated in 23 high income oecd countries by using annual data over 1960 2005 period we utilize lagrange multiplier lm unit root test that endogenously determines structural breaks in level and or trend we find that 21 country series reject the unit root null hypothesis at the 5 significance level except for 2 country series thus our empirical findings provide significant evidence that per capita electricity consumption is stationary in almost all countries considered in the study the stationarity of per capita electricity consumption indicates that it should be possible for the series to forecast future movements in the energy consumption based on the past behaviors of the series important policy implications emerge from our empirical results of the unit root test with multiple structural breaks

new public offerings information and investor rationality the case of publicly offered commodity funds publicly traded commodity funds have been poor investment vehicles yet new funds are a fast growing part of the investment scene in this article the authors show that the information provided to investors is significantly biased upward and that true performance cannot be determined by the information most investors see thus investment in commodity funds given the information set is rational while the authors limit the study to commodity funds the same should hold for other limited partnerships such as real estate oil and gas copyright 1989 by the university of chicago

imperfect competition and the effects of energy price increases on economic activity the authors show that modifying the standard neoclassical growth model by assuming that competition is imperfect makes it easier to explain the size of the declines in output and real wages that follow increases in the price of oil plausibly parameterized models of this type are able to mimic the response of output and real wages in the united states the responses are particularly consistent with a model of implicit collusion where markups depend positively on the ratio of the expected present value of future profits to the current level of output copyright 1996 by ohio state university press

the impact of polycentric development on regional gap of energy efficiency a chinese provincial perspective abstract a reasonable distribution of urban systems is essential for optimizing spatial energy allocation and the quality of economic growth for china this study discusses the impact of the polycentric development on the regional gap of energy efficiency rgee i e difference in energy efficiency levels among cities in the same region in the chinese provincial context by employing a novel method using nighttime lighting data from defense meteorological satellite program s operational linescan system dmsp ols to measure the spatial structure of provinces and stochastic frontier approach sfa to evaluate the total factor energy efficiency our results firstly show that the polycentric development has a narrowing effect on the rgee second they show that the more government intervention can narrow the rgee of a province but being more open having more foreign direct investment fdi and using more coal can widen the rgee of that province meanwhile the level of regional urbanization is shown to have no influence on rgee third they show that the polycentric development has a negative effect on the energy efficiency of large cities but a positive effect on that of small and medium size cities which accordingly narrows the rgee the conclusions of this study not only reveal insights for policies that aim to reduce the rgee but also provide an empirical basis for future urban development strategies in the chinese provincial context

integration of regional electricity markets in australia a price convergence assessment abstract from an electricity market design perspective it is relevant and practical to know which market structures allow for price convergence and how long this takes to achieve this study employs the phillips and sul 2007 2009 methodology to test for the convergence of wholesale electricity prices across the australian states we identify a long run common price growth pattern that applies to a cluster formed by three eastern states that share common market characteristics and limited physical interconnection we also find another cluster with less competitive market structures that although not interconnected strongly converge towards their own trend these findings confirm theoretical expectations while quantifying the rate of convergence finally we also investigate the role that the carbon tax regime has played in the convergence process with new empirical showing that the previous results are not affected with the notable exception being the case of south australia

pricing in social networks we analyze the problem of optimal monopoly pricing in social networks where agents care about consumption or prices of their neighbors we characterize the relation between optimal prices and consumers centrality in the social network this relation depends on the market structure monopoly vs oligopoly and on the type of externalities consumption versus price we identify two situations where the monopolist does not discriminate across nodes in the network linear monopoly with consumption externalities and local monopolies with price externalities we also analyze the robustness of the analysis with respect to changes in demand and the introduction of bargaining between the monopolist and the consumer

long run equilibrium real exchange rates and oil prices abstract using cointegration and causality tests this paper demonstrates that the nonstationary behavior of us dollar real exchange rates over the post bretton woods era is due to the nonstationary behavior of real oil prices

the effects of crude oil shocks on stock market shifts behaviour a regime switching approach abstract in this paper we develop a two regime markov switching egarch model introduced by henry henry o 2009 regime switching in the relationship between equity returns and short term interest rates journal of banking and finance 33 405 414 to examine the relationship between crude oil shocks and stock markets an application to stock markets of uk france and japan over the sample period january 1989 to december 2007 illustrates plausible results we detect two episodes of series behaviour one relative to low mean high variance regime and the other to high mean low variance regime furthermore there is evidence that common recessions coincide with the low mean high variance regime in addition we allow both real stock returns and probability of transitions from one regime to another to depend on the net oil price increase variable the findings show that rises in oil price has a significant role in determining both the volatility of stock returns and the probability of transition across regimes

revenue management under a general discrete choice model of consumer behavior customer choice behavior such as buy up and buy down is an important phenomenon in a wide range of revenue management contexts yet most revenue management methodologies ignore this phenomenon or at best approximate it in a heuristic way in this paper we provide an exact and quite general analysis of this problem specifically we analyze a single leg reserve management problem in which the buyers choice behavior is modeled explicitly the choice model is very general simply specifying the probability of purchase for each fare product as a function of the set of fare products offered the control problem is to decide which subset of fare products to offer at each point in time we show that the optimal policy for this problem has a quite simple form namely it consists of identifying an ordered family of efficient subsets s 1 s m and at each point in time opening one of these sets s k where the optimal index k is increasing in the remaining capacity x and decreasing in the remaining time that is the more capacity or less time available the further the optimal set is along this sequence we also show that the optimal policy is a nested allocation policy if and only if the sequence of efficient sets is nested that is s 1 s 2 s m moreover we give a characterization of when nesting by fare order is optimal we also develop an estimation procedure for this setting based on the expectation maximization em method that jointly estimates arrival rates and choice model parameters when no purchase outcomes are unobservable numerical results are given to illustrate both the model and estimation procedure

convergence in energy consumption per capita among asean countries abstract we test for convergence in energy consumption per capita among asean countries over the period 1971 to 2011 using the panel kpss stationarity test and panel lagrange multiplier lm unit root test the results for the panel stationarity and unit root tests with structural breaks find support for energy convergence in asean

a re examination of stationarity of energy consumption evidence from new unit root tests abstract in this paper we re examine the stochastic behaviour of per capita total primary energy consumption across 178 countries around the world for this purpose in addition to conventional unit root tests we apply newly developed tests that allow for nonlinear adjustments and structural breaks in the data generating process the results of the unit root tests show that allowing for structural breaks and nonlinearity result in more frequent rejection of the null hypothesis of unit root suggesting that most of the series under consideration follow a stationary process these findings imply that both energy economists and policy makers must be careful and take account of possible nonlinearities and structural breaks in their analyses of energy consumption in addition the results imply that government interventions into the energy markets in most countries have no effect in the long run although the short run effects of the interventions depend on the size and the direction of interventions

long memory in us disaggregated petroleum consumption evidence from univariate and multivariate lm tests for fractional integration previous studies that have tested for a unit root in aggregate energy consumption have potentially reached misleading conclusions because they fail to allow for the possibility that energy consumption might be fractionally integrated and do not distinguish between different types of energy consumption this study tests for long memory in disaggregated petroleum consumption in the united states using univariate and multivariate lagrange multiplier lm tests for fractional integration the results point strongly to the need to distinguish between different forms of energy consumption and allow for a generalization of the i 0 i 1 dichotomy when considering the order of integration of energy consumption allowing for short run dynamics the univariate test suggests that less than 50 of the series are fractionally integrated consistent with expectations the non stationary series are found to have the highest mean and standard deviation the multivariate test suggests that petroleum consumption in the commercial and industrial sectors is clearly fractionally integrated when allowing for short run dynamics and as such exhibits persistent effects while petroleum consumption in the residential sector is a stationary process

are co2 emission levels converging among industrial countries time paths of carbon dioxide emissions intwenty one industrial countries are examinedfrom 1960 1997 to test for stochastic andconditional convergence both panel unit roottests and cross section regressions areperformed overall we find significantevidence that co2 emissions haveconverged

structural change and convergence of energy intensity across oecd countries 1970 2005 abstract this paper uses new and unique data derived from a consistent framework of national accounts to compute and evaluate energy intensity developments across 18 oecd countries and 50 sectors over the period 1970 2005 we find that across countries energy intensity levels tend to decrease in most manufacturing sectors in the service sector energy intensity decreases at a relatively slow rate with diverse trends across sub sectors a decomposition analysis reveals that changes in the sectoral composition of the economy explain a considerable and increasing part of aggregate energy intensity dynamics a convergence analysis reveals that only after 1995 cross country variation in aggregate energy intensity levels clearly tends to decrease driven by a strong and robust trend break in manufacturing and enhanced convergence in services moreover we find evidence for the hypothesis that across sectors lagging countries are catching up with leading countries with rates of convergence that are on average higher in services than in manufacturing aggregate convergence patterns are almost exclusively caused by convergence of within sector energy intensity levels and not by convergence of the sectoral composition of economies

are fluctuations in energy consumption per capita transitory evidence from a panel of pacific island countries this study applies the panel stationarity test developed by carrion i silvestre et al 2005 breaking the panels an application to gdp per capita econometrics journal 8 159 175 to examine the stationarity of energy consumption per capita for a panel of 13 pacific island countries over the period 1980 2005 this test has the advantage that it allows for multiple structural breaks at unknown dates that can differ across countries and can account for all forms of cross sectional correlation between countries the conclusion from the study is that energy consumption per capita in approximately 60 of countries is stationary and that energy consumption per capita for the panel as a whole is stationary the study offers several suggestions for modelling energy consumption and policy making in the pacific islands

re examination of convergence hypothesis among indian states in panel stationarity testing framework with structural breaks abstractthis article examines the conditional income convergence hypothesis for 17 major states in india for the period of 1960 2012 univariate stationarity tests without structural breaks provide evidence against the convergence hypothesis however when two or more structural breaks are applied in per capita income series the incomes of around 11 13 states are found to stochastically converge to the national average this finding supports the convergence hypothesis for the panel as a whole after accounting for two data features cross sectional dependence and structural breaks in incomes using a unified panel stationarity testing framework

convergence of per capita sulphur dioxide emissions across us states this study examines the stochastic conditional convergence of sulphur dioxide so2 emissions using the residual augmented least squares lagrange multiplier rals lm unit root test with structural breaks this procedure allows the data to account for trend breaks and nonnormal errors that have been ignored or deemphasized in previous studies the study finds that per capita sulphur dioxide emissions exhibits stochastic conditional convergence across us states

optimizing multinomial logit profit functions the multinomial logit model is a standard approach for determining the probability of purchase in product line problems when the purchase probabilities are multiplied by product contribution margins the resulting profit function is generally nonconcave because of this standard nonlinear search procedures may terminate at a local optimum which is far from the global optimum we present a simple procedure designed to alleviate this problem the key idea of this procedure is to find a path of prices from the global optimum of a related but concave logit profit function to the global optimum of the true but nonconcave logit profit function

electricity intensity convergence in iea oecd countries aggregate and sectoral analysis convergence in electricity intensity is analyzed among a sample of iea countries sigma convergence the narrowing of the distribution and to a lesser degree gamma convergence movement within the distribution are detected however electricity intensity convergence is less dramatic than energy intensity convergence convergence within the end use sectors is more diverse in terms of the rates timing extent and ultimate modal structure of the distributions commercial electricity intensity has more recently converged toward a bell shape distribution by contrast industry electricity intensity is largely converging toward two distinct groups of countries one with relatively high electricity intensity and another one with relatively low electricity intensity different still is related residential electricity consumption per capita where a small group of countries has stopped growing another group has slowed considerably while a third group experienced rapid growth

do per capita health care expenditures converge among oecd countries evidence from unit root tests with level and trend shifts this study examines the stochastic conditional convergence of per capita health care expenditures pchce among 19 oecd countries over the period 1972 2008 specifically newly developed lm and rals lm unit root tests with allowance for two endogenously determined structural breaks are employed the results indicate support for pchce convergence among most oecd countries the results are stronger in more general tests that control for two breaks and nonnormal errors panel unit root tests provide additional support for the stochastic convergence of pchce

energy consumption and gdp in developing countries a cointegrated panel analysis in this paper we re investigate the co movement and the causality relationship between energy consumption and gdp in 18 developing countries using data for the period 1975 to 2001 recently developed tests for the panel unit root heterogeneous panel cointegration and panel based error correction models are employed the empirical results provide clear support of a long run cointegration relationship after allowing for the heterogeneous country effect the long run relationship is estimated using a full modified ols the evidence shows that long run and short run causalities run from energy consumption to gdp but not vice versa this result indicates that energy conservation may harm economic growth in developing countries regardless of being transitory or permanent

the effects of incentive compensation contracts on the risk and return performance of commodity trading advisors this paper shows that commodity trading advisors ctas investment performance may be partially explained by their incentive compensation contracts contracts include base incentive and asset parameters the relationships between contract parameters and performance are theoretically indeterminate but are examined here empirically results indicate that incentive parameters are positively related to return means and standard deviations the dollar amounts of assets ctas manage are negatively related to return means and standard deviations supporting elton et al s 1987 1989 finding that cta performance falls after public offerings of commodity funds intuitively since dollar fees are a function of assets at the higher asset and fee levels achieved through commodity fund offerings ctas may safeguard assets and fees by pursuing less risky investment strategies

a multinomial choice model of neighborhood effects this paper provides a model of individual decisionmaking in the presence of neighborhood effects by neighborhood effects we refer to interdependencies between individual decisions and the decisions and characteristics of others within a common neighborhood as such neighborhood effects are forms of social interactions in fact the terms would seem to be interchangeable in many contexts within economics there has developed an increasing recognition that neighborhood effects play a possibly major role in explaining a range of individual behaviors rich empirical and theoretical literatures have developed a failing of much of this work is the absence of strong connections between theory and empirics this paper addresses this limitation by providing a model of multinomial choice with neighborhood effects the model represents a generalization of the binary choice model of william brock and steven durlauf 2001a b the model is econometrically implementable and so has the potential of allowing for structural estimation of neighborhood effects section i outlines a basic choice model with neighborhood effects section ii specializes the structure using a multinomial logit framework section iii considers econometric implementation section iv discusses some limitations of the framework and proposes some research directions proofs of all theorems may be found in brock and durlauf 2001c

optimal pricing in networks with externalities we study the optimal pricing strategies of a monopolist selling a divisible good service to consumers who are embedded in a social network a key feature of our model is that consumers experience a positive local network effect in particular each consumer s usage level depends directly on the usage of her neighbors in the social network structure thus the monopolist s optimal pricing strategy may involve offering discounts to certain agents who have a central position in the underlying network our results can be summarized as follows first we consider a setting where the monopolist can offer individualized prices and derive a characterization of the optimal price for each consumer as a function of her network position in particular we show that it is optimal for the monopolist to charge each agent a price that consists of three components i a nominal term that is independent of the network structure ii a discount term proportional to the influence that this agent exerts over the rest of the social network quantified by the agent s bonacich centrality and iii a markup term proportional to the influence that the network exerts on the agent in the second part of the paper we discuss the optimal strategy of a monopolist who can only choose a single uniform price for the good and derive an algorithm polynomial in the number of agents to compute such a price third we assume that the monopolist can offer the good in two prices full and discounted and we study the problem of determining which set of consumers should be given the discount we show that the problem is np hard however we provide an explicit characterization of the set of agents who should be offered the discounted price next we describe an approximation algorithm for finding the optimal set of agents we show that if the profit is nonnegative under any feasible price allocation the algorithm guarantees at least 88 of the optimal profit finally we highlight the value of network information by comparing the profits of a monopolist who does not take into account the network effects when choosing her pricing policy to those of a monopolist who uses this information optimally

are oil shocks permanent or temporary panel data evidence from crude oil and ngl production in 60 countries this paper examines the unit root properties of crude oil production for 60 countries employing a range of panel data unit root tests for the period 1971 to 2003 the study first employs a number of panel data tests that do not accommodate structural breaks and then proceeds to apply the lagrange multiplier lm panel unit root test with one structural break the results of the panel data tests without a structural break are inconclusive with at best mixed support for joint stationarity the findings from the lm panel unit root test with a structural break however are conclusive suggesting that for a world panel and smaller regional based panels crude oil and ngl production are jointly stationary

is energy consumption per capita broken stationary new evidence from regional based panels abstract for the first time a new panel unit root testing procedure developed by 51 carrion i silvestre et al 2005 breaking the panels an application to gdp per capita econometrics journal 8 159 175 is applied to re investigate the stationarity of energy consumption per capita for 7 regional panel sets covering the 1971 2002 period with structural breaks and cross sectional correlations introduced into the model it becomes clear that all regional based panels of energy consumption per capita are stationary the structural breakpoints identify the likely causes of major changes in energy consumption in the past the findings underscore the importance of accounting for exogenous shocks to a series and offer several important implications for policy makers and energy economists

china s energy intensity target allocation needs improvement lessons from the convergence analysis of energy intensity across chinese provinces abstract to explore the reasonability of the decomposition of china s national energy intensity target we tested the convergence of energy intensity across 30 chinese provinces including stochastic convergence convergence and o convergence based on panel data from 30 chinese provinces across three five year plan periods the results confirmed the existence of stochastic convergence and convergence but did not prove the existence of o convergence in china s energy intensity in addition by comparing the convergence speed over the three five year plan periods the results showed that china s energy intensity targets for the provinces slowed convergence in energy intensity during the 11th and 12th five year plan periods highlighting the need to optimize the decomposition of china s national energy intensity target finally issues related to the decomposition of china s national energy intensity target were discussed and policy suggestions were proposed to optimize it from the perspective of promoting the convergence of energy intensity across chinese provinces

are investors rational choices among index funds s p 500 index funds represent one of the simplest vehicles for examining rational behavior they hold virtually the same securities yet their returns differ by more than 2 percent per year although the relative returns of alternative s p 500 funds are easily predictable the relationship between cash flows and performance is weaker than rational behavior would lead us to expect we show that selecting funds based on low expenses or high past returns outperforms the portfolio of index funds selected by investors our results exemplify the fact that in a market where arbitrage is not possible dominated products can prosper

are shocks to natural gas consumption temporary or permanent evidence from a panel of u s states abstract this short communication examines whether or not u s natural gas consumption follows a stationary process unlike previous research that has focused on regional country or industrial sector based panel studies this study undertakes a sub national investigation of natural gas consumption for the 50 u s states levin et al 2002 im et al 2003 maddala and wu 1999 and hadri 2000 panel unit root and stationarity tests reveal that natural gas consumption is integrated of order one however once allowance is made for endogenously determined structural breaks the carrion i silvestre et al 2005 im et al 2005 and westerlund 2005 panel unit root and stationarity tests indicate that natural gas consumption is integrated of order zero discussion of the structural breaks is briefly surveyed in relation to the natural gas industry s response to legislative actions

energy demand convergence in apec an empirical analysis this paper empirically examines the cross country convergence of per capita energy and electricity usage in apec a significant economic bloc to this end the study applies conventional panel unit root tests and sequential panel selection model spsm procedure based on the panel kss unit root with a fourier function for robustness analysis the results from conventional unit root test results indicate that per capita energy usage and electricity consumption are converging for all apec countries in line with improving living standards in apec the findings also provide some support for policies to promote energy integration among apec countries according to spsm analysis evidence of energy convergence is found for 15 out of 19 apec countries and evidence of electricity convergence is found for 17 out of 19 apec countries pursuit of policies to achieve energy supply stability can move divergent countries toward convergence

the world per capita electricity consumption distribution signs of convergence abstract considering residential per capita electricity consumption as one of the most suitable economic welfare indicators the aim of this paper is to explore worldwide differences on this variable over the period 1980 2007 the paper adds to the standard practice of and convergence analysis by tracking the external shape and time evolution of the entire distribution applying nonparametric techniques density functions and stochastic kernels to a sample of 98 countries the main finding is that a weak process of electricity consumption convergence has taken place this reduction of disparities is clearly related to at least three issues firstly the rapid economic changes experienced by some developing countries secondly the energy conservation policies implemented by most developed countries following the first oil shock and thirdly the growing awareness on energy issues in rich countries notwithstanding this the ergodic distribution on per capita electricity consumption indicates that large cross country disparities will persist in the long run

structural break unit root and the causality between energy consumption and gdp in turkey abstract this paper tries to investigate a series of unit root and causality tests to detect causality between the gdp and energy consumption in turkey employing hsiao s version of granger causality method for the 1950 2000 period the conventional unit root tests indicate the series are i 1 whereas the endogenous break unit root tests proposed by zivot and andrews zivot e and andrews d w k 1992 further evidence on the great crash the oil price shock and the unit root hypothesis journal of business and economics statistics 10 251 270 and perron perron p 1997 further evidence on breaking trend functions in macroeconomic variables journal of econometrics 80 355 385 reveal that the series are trend stationary with a structural break therefore it is inappropriate to take the first difference of the data to achieve stationarity the main conclusion of this study is that there is no evidence of causality between energy consumption and gdp in turkey based on the detrended data

the asymmetric effects of oil price and monetary policy shocks a nonlinear var approach in this paper we investigate the asymmetric effects of oil price shocks and monetary policy on macroeconomic activity using monthly data for the united states over the period from 1983 1 to 2008 12 in doing so we use a logistic smooth transition vector autoregression var as detailed in terasvirta and anderson 1992 and weise 1999 and make a distinction between two oil price volatility regimes high and low using the realized oil price volatility as a switching variable we isolate the effects of oil price and monetary policy shocks and their asymmetry on output growth and following koop et al 1996 and weise 1999 we employ simulation methods to calculate generalized impulse response functions girfs to trace the effects of independent shocks on the conditional means of the variables our results suggest that in addition to the price of oil oil price volatility has an impact on macroeconomic activity and that monetary policy is not only reinforcing the effects of oil price shocks on output it is also contributing to the asymmetric response of output to oil price shocks

is the consumption income ratio stationary in african countries evidence from new time series tests that allow for structural breaks abstractthis article examines whether the consumption income ratio is stationary in 50 african countries we use the residual augmented least squares rals lm unit root test that allows for struct

time varying smooth transition autoregressive models nonlinear regime switching behavior and structural change are often perceived as competing alternatives to linearity in this article we study the so called time varying smooth transition autoregressive tv star model which can be used both for describing simultaneous nonlinearity and structural change and for distinguishing between these features two modeling strategies for empirical specification of tv star models are developed monte carlo simulations show that neither of the two strategies dominates the other a specific to general to specific procedure is best suited for obtaining a first impression of the importance of nonlinearity and or structural change for a particular time series a specific to general procedure is most useful in careful specification of a model with nonlinear and or time varying properties an empirical application to a large dataset of u s macroeconomic time series illustrates the relative merits of both modeling strategies

an analysis of oil production by opec countries persistence breaks and outliers this study examines the time series behaviour of oil production for opec member countries within a fractional integration modelling framework recognizing the potential for structural breaks and outliers the analysis is undertaken using monthly data from january 1973 to october 2008 for 13 opec member countries the results indicate there is mean reverting persistence in oil production with breaks identified in 10 out of the 13 countries examined thus shocks affecting the structure of opec oil production will have persistent effects in the long run for all countries and in some cases the effects are expected to be permanent

evidence of long memory behavior in u s renewable energy consumption this study examines the degrees of time persistence in u s total renewable energy consumption using innovative fractional integration and autoregressive models with monthly data from 1981 1 to 2010 10 the results indicate that renewable energy consumption is better explained in terms of a long memory model that incorporates persistence components and seasonality the degree of integration is above 0 5 but significantly below 1 0 suggesting nonstationarity with mean reverting behavior the presence of long memory behavior persistence in renewable energy consumption suggests that random shocks may very well move renewable energy consumption from pre determined target levels for a period of time

oil price and inflation abstract an oil price rise would be expected to result in an immediate reduction by about 20 in the standard of living of the oil importing countries and a corresponding increase in that of the oil exporters since the price rises experienced during recent years have not been reflected in wage reductions the result has been high long lasting inflation which this paper shows will increase in the coming years to more than 20 measures taken by the oil importers include energy saving which results in a still lower standard of living if instead the industrialized countries increase production by increasing energy consumption and improving production efficiency the effect of a rise in oil price will be compensated for in a few years

applied econometrics and implications for energy economics research abstract developments in applied econometrics particularly with regard to unit root tests and cointegration tests have motivated a rich empirical literature on energy economics over the last decade this study reviews recent developments in time series econometrics applications in the energy economics literature we first consider the literature on the integration properties of energy variables we begin with a discussion of the implications of whether energy variables contain a unit root and proceed to examine how results differ according to the specific unit root or stationarity test employed we then proceed to examine recent developments in the literature on cointegration granger causality and long run estimates between disaggregated energy consumption and economic growth we review both single country and panel studies and pay particular attention to studies which have expanded the literature through adding variables such as financial development and trade in addition to energy consumption to the augmented production function as well as studies which have extended the literature through examining disaggregated energy consumption by type in each case we highlight best practice in the literature point to limitations in the literature including econometric modeling challenges and suggest recommendations for future research a key message of our survey is that the profession needs to guard against overload of research in these areas as most applied studies are no longer adding anything more to what is already known

have air pollutant emissions converged among u s regions evidence from unit root tests previous studies of income distribution have found evidence indicating that incomes across u s regions have converged supporting the prediction of the neoclassical growth model a potential shortcoming in these studies is that only one measure of well being is considered a measure of wealth linked to incomes or production this paper examines whether income convergence was accompanied by air pollutant emission convergence results from unit root tests provide some evidence that indicators of environmental quality have converged across u s regions during the 1929 1994 period

the reverse lbo decision and firm performance theory and evidence we investigate the transition from private to public ownership of companies that had previously been subject to leveraged buyouts lbos we show that the information asymmetry problem firms face when they go to public markets for equity as well as behavioral and debt overhang effects will produce a pattern in which superior performance before an offering should be expected with disappointing performance subsequently we find empirical evidence of this phenomenon by studying 62 reverse lbos that went public between 1983 and 1987 the market appears to anticipate this pattern in 1991 56 leveraged buyouts lbos returned to the public equity markets part of a broader phenomenon in which a large fraction of lbos go public again hence becoming reverse lbos kaplan 1991 reports that 45 percent of a sample of large lbos completed between 1979 and 1986 later returned to public ownership moreover reverse lbos tend to be larger than the average initial public offering ipo 1 in sum transitions from the lbo form to public ownership have become a widespread and economically significant phenomenon we find strong evidence that the return to public ownership of reverse lbos coincides with a peak in their operating performance their operating income as a percentage of total assets grew by about seven percentage points in the preoffering year comparison firms in the same industries show a slight decline in the same performance measure moreover in the preoffering year reverse lbos outperform continuing lbos in the year after the

will history repeat itself economic convergence and convergence in energy use patterns in this paper a difference in differences estimator on panel data for 30 developing and 21 industrialized countries is employed over the period 1971 2005 to examine how patterns of energy use characterized by the consumption of primary energy carriers sectoral energy use and carbon emissions are changing in the process of economic development for the average developing country in our sample the results indicate that economic catch up has been accompanied by above average growth of the use of most primary energy carriers the consumption of final energy in most sectors and total co2 emissions for industrialized countries we find that economic growth is partially decoupled from energy consumption and that above average rates of economic growth were accompanied by larger improvements in energy efficiency these results emphasize the need to identify the relevant engines of economic growth their implications for energy use and possibilities to achieve low carbon growth centered on productivity and efficiency improvements rather than on capital accumulation

optimal pricing for a multinomial logit choice model with network effects we consider a seller s problem of determining revenue maximizing prices for an assortment of products that exhibit network effects customers make purchase decisions according to a multinomial logit choice model modified to incorporate network effects so that the utility each individual customer gains from purchasing a particular product depends on the market s total consumption of that product in the setting of homogeneous products we show that if the network effect is comparatively weak then the optimal pricing decision of the seller is to set identical prices for all products however if the network effect is strong then the optimal pricing decision is to set the price of one product low and to set the prices of all other products to a single high value this boosts the sales of the single low price product in comparison to the sales of all other products we also obtain comparative statics results that describe how optimal prices and sales levels vary with a parameter that determines the strengt

divergence in state level per capita carbon dioxide emissions this paper addresses the question of whether income convergence is sufficient for per capita carbon dioxide co2 emissions convergence by focusing on a set of advanced economies the u s states i undertake a variety of cross sectional and stochastic convergence tests with two novel measures of 1960 to 1999 state level co2 emissions per capita production pre electricity trade co2 and consumption post electricity trade co2 and with income per capita although incomes continue to converge i find stark divergence in production co2 per capita and no evidence of convergence for consumption co2 per capita forecasts of future distributions show little convergence in emissions

testing for convergence in electricity consumption across croatian regions at the consumer s sectoral level abstract using the panel unit tests with and without structural break s the convergence hypothesis in relative per capita electricity consumption series is tested across croatian regions during the period 2001 2013 the results are mixed depending primarily on the consumption sector considered and the test applied they indicate the necessity to conduct analysis and formulate energy policy measures on the sector disaggregated and regional specific electricity consumption time series the croatian electricity markets are not fully integrated and some regions are faced with statistically significant structural break s demonstrating thereby the croatian gradual energy reform process with several sudden innovations significant regional differences and the market dependence on expectations domestic and international economic and non economic innovations the impacts of innovations are likely to be permanent for most of the regions and their electricity consumption behaviours are likely to be path dependent consequently innovations into the energy markets including government interventions may have long run effects indicating that space and time for experimenting with alternative mechanisms are quite limited

towards a common renewable future the system gmm approach to assess the convergence in renewable energy consumption of eu countries abstract this paper investigates whether the contribution of renewable energy sources to primary energy consumption is characterized by a convergence process across core european union eu countries over the period from 1990 to 2014 the system generalized method of moments gmm methodology is employed for 5 year span panel data of 14 eu members the findings indicate strong evidence for both the absolute unconditional and conditional convergence of renewables share in primary energy consumption across eu 14 countries moreover the control variables namely co2 emissions per gdp fdi inward stock and electricity prices contribute to the speed of convergence hence the implicit rate of conditional convergence is higher than that of absolute convergence the empirical evidence suggests that the energy mixes of core eu members have a tendency to become similar in the long run as the shares of res in primary energy consumption converge to the average level nonetheless it does not necessarily imply that this average would be 20 target which is to be achieved by 2020 according to eu directive 2009 28 ec

new equity funds marketing and performance we discuss two strategies sponsors have used successfully to introduce new equity funds and promote the performance of the funds after their introduction the strategy of incubation allows funds that compile a favorable track record in private to be marketed to the public at a later opportune time the strategy of selective attention directs favorable allocations of special situations into new funds that are open to the public introduction strategies are most apparent among aggressive growth funds where first year performance has increasingly become superior incubator funds remain small while private but once opened they quickly increase in size and revert to median performance the first year success of selective attention funds also attracts large amounts of cash which undermines their subsequent performance

on the relationship between inventory costs and variety benefits in retailassortments consider a category of product variants distinguished by some attribute such as color or flavor a retailer must construct an assortment for the category i e select a subset variants to stock and determine purchase quantities for each offered variant we analyze this problem using a multinomial logit model to describe the consumer choice process and a newsboy model to represent the retailer s inventory cost we show that the optimal assortment has a simple structure and provide insights on how various factors affect the optimal level of assortment variety we also develop a formal definition of the level of fashion in a category using the theory of majorization and examine its implications for category profits

income and co2 emissions evidence from panel unit root and cointegration tests abstract this paper re investigates the stationarity properties of per capita carbon dioxide co 2 emissions and real gross domestic product gdp per capita for 109 countries within seven regional panel sets covering 1971 2003 we apply the recent unit root test of the panel seemingly unrelated regressions augmented dickey fuller suradf test developed by breuer et al 2001 misleading inferences from panel unit root tests with an illustration from purchasing power parity review of international economics 9 482 493 2002 series specific unit root tests with panel data oxford bulletin of economics and statistics 64 527 546 the panel suradf test accounts for the presence of cross country correlations in the data and the parameters in the panel specification vary across countries more importantly this test allows us to identify how many and which members of the panel contain a unit root overall our empirical results illustrate that real gdp and co 2 emissions in these countries are a mixture of i 0 and i 1 processes and that the traditional panel unit root tests could lead to misleading inferences as well as the conduct of cointegration analysis being perhaps inappropriate the results of our analysis carry critical implications for the modeling of co 2 emissions and gdp because of the different orders of integration for the two variables

unit root properties of crude oil spot and futures prices in this article we examine whether wti and brent crude oil spot and futures prices at 1 3 and 6 months to maturity contain a unit root with one and two structural breaks employing weekly data over the period 1991 2004 to realise this objective we employ lagrange multiplier lm unit root tests with one and two endogenous structural breaks proposed by lee and strazicich 2003 minimum lagrange multiplier unit root test with two structural breaks review of economics and statistics 85 1082 1089 2004 minimum lm unit root test with one structural break working paper no 04 17 department of economics appalachian state university we find that each of the oil price series can be characterised as a random walk process and that the endogenous structural breaks are significant and meaningful in terms of events that have impacted on world oil markets

multiple product firms a nested logit approach this paper proves the existence of a symmetric equilibrium with multiproduct firms using a nested logit model of demand the demand model is parameterized by two variables that characterize different dimensions of preference for variety these reflect intragroup heterogeneity and intergroup heterogeneity a group or nest being the set of products produced by a firm there are then two dimensions to market performance the total number of firms and the range of products produced per firm it is shown that the market equilibrium involves an excessive number of firms but each firm provides too few products copyright 1992 by blackwell publishing ltd