rockets and feathers understanding asymmetric pricing prices rise like rockets but fall like feathers this stylized fact of most markets is con rmed by many empirical studies in this paper i develop a model with competitive rms and rational partially informed consumers where such asymmetric response to costs by rms emerges naturally in contrast to public opinion and past work collusion is not necessary to explain such result using a rich dataset of retail gasoline prices i nd the observed price dispersion pattern to be consistent with the model s prediction

the dynamics pattern of price dispersion in retail fuel markets abstract this paper empirically investigates the dynamics of price dispersion in retail fuel markets as a response to the corresponding wholesale price changes for this purpose we take advantage of a daily dataset of prices fixed by gas stations in two spanish regions it is consistently found that retail price dispersion is temporarily enlarged as a consequence of wholesale price increases while it is reduced due to decreases the presence of asymmetries in the short run dynamics is also revealed the impact of positive changes in the wholesale price is in the first days of adjustment clearly greater the dynamics pattern could be explained at least in part by the faster response of prices in the stations associated with the two vertically integrated companies that have the largest market share i e repsol and cepsa

the costs of low birth weight birth weight has emerged as the leading indicator of infant health and welfare and the central focus of infant health policy this is because low birth weight lbw infants experience severe health and developmental difficulties that can impose enormous costs on society but would the prevention of lbw generate equally sizable cost savings and health improvements estimates of the return to lbwprevention from cross sectional associations may be biased by omitted variables that cannot be influenced by policy such as genetic factors to address this we compare the hospital costs health at birth and infant mortality rates between heavier and lighter infants from all twin pairs born in the united states we also examine the effect of maternal smoking during pregnancy the leading risk factor for lbw in the united states on health among singleton births after controlling for detailed background characteristics both analyses imply substantially smaller effects of lbw than previously thought suggesting two possibilities 1 existing estimates overstate the true costs and consequences of lbw by at least a factor of four and by as much as a factor of 20 or 2 different lbw preventing interventions have different health and cost consequences implying that policy efforts that presume a single return to reducing lbw will necessarily be suboptimal

vertical relationships and competition in retail gasoline markets empirical evidence from contract changes in southern california comment this study examines how much if any of the differences in retail gasoline prices between markets is attributable to differences in the composition of vertical contract types at gasoline stations in each market the purchase of the independent retail gasoline chain thrifty by arco provides a unique opportunity to examine the effects of changes in different vertical contract types on local retail prices this event caused sharp changes in the market share of i fully vertically integrated stations and ii independent stations differentially affecting local markets in the los angeles and san diego metropolitan areas using unique and detailed station level data this study examines how these sharp changes affected local retail prices the detailed data and the research design based on the thrifty station conversions allow for credible estimation of the effects of the market share of independent retailers and vertically integrated retailers on local market prices controlling for any omitted factors at the station level and the city level over time results for the los angeles and san diego metropolitan areas indicate that a decrease in the market share of independent stations has a significant positive impact on local retail price however a change in the market share of refiner owned and operated branded stations does not have a significant impact on local market price these results have important implications as policy makers consider the regulation of vertical contracts as a means to increase competition in gasoline markets the research design and detailed data also allow for inference on the underlying nature of retail gasoline competition

screening and mitigation of exacerbated market power due to financial transmission rights a methodology is proposed for taking into account potential exacerbation of market power due to financial transmission rights ftr allocations hedging position ratios hprs are computed for ftr bids these ratios quantify the relationship between the positions of an ftr bidder in the energy market and in the transmission rights allocation based on the transmission rights bids these ratios are used to identify the potential gambling positions from the transmission rights bidders and therefore used to prioritize critical positions in the auction the transmission right auction is modeled as a quadratic programming problem with a direct current dc approximation the methodology is illustrated by a three node network and then extended to larger networks

a unifying market power measure for deregulated transmission constrained electricity markets market power assessment is a prime concern when designing a deregulated electricity market in this paper we propose a new functional market power measure termed transmission constrained network flow tcnf that unifies three large classes of transmission constrained structural market power indices in the literature residual supply based network flow based and minimal generation based furthermore it is suitable for demand response and renewable integration and hence more amenable to identifying market power in the future smart grid the measure is defined abstractly and allows incorporation of power flow equations in multiple ways we investigate the current market operations using a dc approximation and further explore the possibility of including detailed ac power flow models through semidefinite relaxation and interior point algorithms from matpower finally we provide extensive simulations on ieee benchmark systems and highlight the complex interaction of engineering constraints with market power assessment

locational market power screening and congestion management experience and suggestions the existing new england electricity market follows a uniform pricing system inframarginal generators are paid a uniform clearing price while constrained on generators are paid bid prices subject to a locational market power screen in this paper we first report the operation experience of this approach during the market s first two years we then briefly review the new england power system nepool locational pricing proposal being implemented two new approaches for locational market power screening are presented the first one is based on a zonal network model and the second is based on a nodal transmission model both approaches are being evaluated by an independent consultant and are be to recommended to nepool test results of both approaches are included

divestiture requirements as a tool for competition policy a case from the swedish beer market we investigate the effect of divestitures on prices and welfare following the carlsberg pripps merger in the swedish beer market both difference in difference estimation and simulations using a random coefficients logit model suggest that divestitures are important for dampening price increases prices of divested brands fall by around 3 and the predicted price increase for carlsberg falls from 3 to 1 6 as a result of the divestitures to guide practice on divestitures we investigate the role of the recipient and the number and characteristics of the divested products by simulating post merger outcomes for all relevant cases we find that in this setting with large multiproduct firms the competition authority s most effective means to dampen adverse post merger outcomes are to aim for a small recipient firm and attain a large number of divested products enforcing larger divestitures in terms of market share and raising the average cross price elasticity between the merging parties divested and retained products strengthen the dampening effect further

viewpoint replication in economics this examination of the role and potential for replication in economics points out the paucity of both pure replication checking on others published papers using their data and scientific replication using data representing different populations in one s own work or in a comment several controversies in empirical economics are used to illustrate how and how not to behave when replicating others work the incentives for replication are examined and proposals aimed at journal editors and authors are advanced that might stimulate an activity that most economists applaud but few perform

the tc psi indicator for forecasting the potential for market power in wholesale electricity markets abstract wholesale electricity market regulators have long sought a simple reliable transparent indicator of the likely impact of wholesale market developments on the exercise of market power conventional indicators such as the pivotal supplier indicator psi and the residual supply index rsi cannot be extended to apply to meshed transmission networks especially when generating companies hold a portfolio of generating units at different locations on the network this paper proposes a generalisation of these standard measures termed the transmission constrained pivotal supplier indicator tc psi the tc psi of a generating company is defined as the maximum must run generation for any subset of generating plant while allowing for strategic operation of other plant in the portfolio we illustrate the use of the tc psi using a five node model of the australian nem

oligopolistic pricing with sequential consumer search n identical stores compete by choosing prices for a homogeneous good with constant marginal costs consumers search sequentially with perfect recall for the lowest price one class of consumers called shoppers have zero search costs while all other consumers have a positive search cost c there is a unique symmetric nash equilibrium price distribution with the property that it changes smoothly from marginal cost pricing when all consumers are shoppers and or c 0 and monopoly pricing when no consumers are shoppers remarkably as the number of stores increases the nash equilibrium becomes more monopolistic copyright 1989 by american economic association

taxes cost and demand shifters as determinants in the regional gasoline price formation process evidence from spain abstract this paper examines the pass through of regional tax changes and spot price variations to regional gasoline prices in spain it also analyzes the impact of all major cost and demand shifters that contribute to regional gasoline price formation to address these research issues a reduced form price equation using monthly time series cross sectional tscs data from january 2004 through december 2008 is estimated strong and consistent evidence of full shifting of regional tax changes to regional gasoline prices is found gasoline spot price changes are more than proportionally passed through to retail prices in addition the empirical evidence shows on the one hand that regional gasoline price differences before taxes continue to be quite narrow and on the other hand that there is still a margin for larger gasoline price differences among regions this suggest that traditional practices from the monopoly era i e relatively uniform regional gasoline prices persist after the market has been liberalized which may have been facilitated by the strong and uniform presence of the major spanish based refining companies in the retail sector over the whole country

reactive market power analysis using must run indices this paper investigates the issues of reactive power must run capacity in power system operations hence in electricity markets a must run index based method is proposed in the paper to measure the market power held by reactive power suppliers the nordic 32 bus system and the ieee 118 bus system are used to test the proposed method the market power holders of reactive power found using the proposed method are in accord with that found in the realistic nordic system operation and in the existing analysis of ieee 118 bus system the paper identifies through must run indices possible conditions that could lead to market power in the case of applying a bid structure within a market framework furthermore market structure drawbacks can cause the appearance of market power even in a topologically ideal system

consumer and competitor reactions evidence from a field experiment abstract in response to a price change by a single seller it is common for the density of sellers in the market to influence both the quantity response of consumers and the price response of other sellers using field experiment data collected around a series of exogenously imposed price changes we find that an individual retailer with a larger number of competitors faces a more responsive demand this finding is fundamental to a predicted inverse relationship between market prices and the number of competitors we also examine the reaction of rival stations to exogenous price changes and find that the magnitude of a competitor s response is inversely related to the density of stations in the market

conjectures firm characteristics and market structure abstract this paper makes use of a unique data set to investigate how firms in the vancouver british columbia retail gasoline market view their rivals and how consumers in turn view these firms own and rival price elasticities of demand conjectural variations and lerner indices are estimated for thirteen service stations in a submarket of vancouver these variables are then related to firm characteristics such as type of ownership degree of horizontal and vertical integration and type of service in this way systematic patterns in seller behavior and in buyer attitudes are revealed

on the properties of nodal price response matrix in electricity markets we establish sufficient conditions for nodal price response matrix in electric power system to be symmetric and negative semi definite the results are applicable for electricity markets with nonlinear and intertemporal constraints

market power vertical integration and the wholesale price of gasoline this paper examines empirically the relationship between vertical integration and wholesale gasoline prices we use discrete and differential changes in the extent of vertical integration generated by mergers in west coast gasoline refining and retailing markets to test for incentives to raise rivals costs the research design allows us to test for a relationship between vertical integration and wholesale prices controlling for horizontal market structure cost shocks and trends we find evidence consistent with the strategic incentive to raise competitors input costs this suggests that vertical integration can have a significant impact on wholesale prices

economic inefficiencies and cross subsidies in an auction based electricity pool this paper compares two contrasting yet often used electricity market clearing procedures i an auction based algorithm including congestion management and transmission loss cost allocation and ii an optimal power flow the auction procedure produces a single period unit commitment and hence can be compared directly to an optimal power flow solution these algorithms are compared in terms of the economic efficiency of the solution attained and in terms of cross subsidies among generators and demands the purpose of this comparison is to quantify the actual cost to market participants of using a simple seemingly transparent procedure such as an auction based algorithm versus an integrated but computationally intensive one such as an optimal power flow

short term market power assessment in a long term dynamic modeling of capacity investment this paper proposes a dynamic time simulation model for long term generation capacity investment decisions in the presence of either perfect or imperfect electricity market the model is based on system dynamics concept in which the dynamics of capacity construction is traced using the forecast of electricity price cleared in the short term electricity market both the perfect and oligopolistic competitions are considered and a market power index is defined to evaluate the competition level of the electricity market the short term and long term dynamic analysis are used to represent the generation firms behavior in bidding strategy and capacity investment respectively both possibilities of using forward bilateral contracts and application of wind power generation have been assessed individually in the proposed model in order to mitigate the market power the time simulation results derived from a case study demonstrate the effectiveness of the model in illustrating the oligopoly in electricity marketplace and also the alternative decisions to attenuate it such a decision tool enables both the generation firms and the regulators to gain perfect insight into the oligopoly and its consequences in the long term capacity investment in the electricity market

risk limiting economic dispatch for electricity markets with flexible ramping products the expected increase in the penetration of renewables in the approaching decade urges the electricity market to introduce new products in particular flexible ramping products to accommodate the renewables variability and intermittency a risk limiting economic dispatch scheme provides the means to optimize the dispatch and provision of these products in this paper we adopt the extended loss of load probability as the definition of risk we first assess how the new products distort the optimal economic dispatch by comparing to the case without such products specifically using parametric analysis we establish the relationship between the minimal generation cost and the two key parameters of the new products the up and down flexible ramping requirements such relationship yields a novel routine to efficiently solve the non convex risk limiting economic dispatch problem both theoretical analysis and simulation results suggest that our approach may substantially reduce the cost for incorporating the new products we believe our approach can assist the isos with utilizing the ramping capacities in the system at the minimal cost

nodal market power assessment in electricity markets market power assessment is an important aspect of electric market analysis and operation market power problems are more complicated in an electric market than those in other markets due to the specific properties of electricity this paper investigates market power problems and the related solution techniques in an electric power market the impact of load variation the size of a power supplier and random failures on market power has been investigated the geographic difference of market power caused by network constraints has been considered must run share mrs and nodal must run share nmrs have been proposed to represent system and local market powers respectively an optimization technique and the topological analysis of power flow have been used to determine the mrs and nmrs expected nodal must run share enmrs has been proposed to represent the impact of random failures on market power and the associated risk of customers paying a high price due to the exercise of market power the contingency enumeration and probabilistic technique have been used to determine the enmrs the ieee reliability test system is analyzed to illustrate the proposed indices and techniques

the effects of different contractual arrangements the case of retail gasoline markets the change in the contractual arrangement at a gasoline station from a refiner controlled to a franchise operation implies different incentives for the individual who sets prices and determines hours but reflects no change in the product nor the market environment the outcome can lead to higher prices and reduced hours at the station affected the divorcement experience in maryland illustrates how change can be imposed by the legal system average self service and full serve prices rose and hours of operation fell relative to those of competitors even though refiner operations that were forced to franchise had previously had prices below the competition the evidence of an effect on the prices and hours of competitors is less convincing 16 references 2 tables

vertical antitrust policy as a problem of inference the legality of nonprice vertical practices in the u s is determined by their likely competitive effects an optimal enforcement rule combines evidence with theory to update prior beliefs and specifies a decision that minimizes the expected loss because the welfare effects of vertical practices are theoretically ambiguous optimal decisions depend heavily on prior beliefs which should be guided by empirical evidence empirically vertical restraints appear to reduce price and or increase output thus absent a good natural experiment to evaluate a particular restraint s effect an optimal policy places a heavy burden on plaintiffs to show that a restraint is anticompetitive

empirical studies of gasoline retailing a guide to the literature abstract this paper surveys the empirical literature on gasoline retailing which has been growing rapidly over the last three decades possibly in response to antitrust and regulatory concerns and increased availability of pricing data studies of both pricing and non price decision variables are considered in general it is found that crude oil prices are the primary driver of national price movements over time however market structure has been identified as playing a role in price dynamics equilibrium selection and price differentials across markets and stations the economic literature emphasizes the importance of heterogeneity across stations and coordination problems faced by retailers several directions for future work are suggested including the development of theory and demand estimation using high frequency station level data

seasonal cointegration for monthly data abstract in this paper we propose an extension of the maximum likelihood seasonal cointegration procedure developed by johansen and schaumburg j economet 88 1999 310 for monthly time series we compute the finite sample critical values of the associated test statistics in monthly seasonal time series we also apply this seasonal cointegration procedure to the retails and stocks in us monthly manufacturing industrial data

vertical integration and firm boundaries the evidence since ronald h coase s 1937 seminal paper a rich set of theories has been developed that deal with firm boundaries in vertical or input output structures in the last twenty five years empirical evidence that can shed light on those theories also has been accumulating we review the findings of empirical studies that have addressed two main interrelated questions first what types of transactions are best brought within the firm and second what are the consequences of vertical integration decisions for economic outcomes such as prices quantities investment and profits throughout we highlight areas of potential cross fertilization and promising areas for future work

retail gasoline price dynamics and local market power using monthly data from the 48 contiguous states except nevada for the 1988 2002 period it is shown that retail gasoline prices respond faster to wholesale price increases than to equivalent wholesale price decreases moreover markets with high average retail wholesale margins experience a slower adjustment and a more asymmetric response since gasoline is the only variable input average margins in a state likely reflect the degree of retail market power this suggests that sticky prices and response asymmetries in the gasoline market are at least partially a consequence of retail market power

the credibility revolution in empirical economics how better research design is taking the con out of econometrics since edward leamer s memorable 1983 paper let s take the con out of econometrics empirical microeconomics has experienced a credibility revolution while leamer s suggested remedy sensitivity analysis has played a role in this we argue that the primary engine driving improvement has been a focus on the quality of empirical research designs the advantages of a good research design are perhaps most easily apparent in research using random assignment we begin with an overview of leamer s 1983 critique and his proposed remedies we then turn to the key factors we see contributing to improved empirical work including the availability of more and better data along with advances in theoretical econometric understanding but especially the fact that research design has moved front and center in much of empirical micro we offer a brief digression into macroeconomics and industrial organization where progress by our lights is less dramatic although there is work in both fields that we find encouraging finally we discuss the view that the design pendulum has swung too far critics of design driven studies argue that in pursuit of clean and credible research designs researchers seek good answers instead of good questions we briefly respond to this concern which worries us little

2 00 gas studying the effects of a gas tax moratorium there are surprisingly few estimates of the effects of sales taxes on retail prices especially at the firm level we consider the temporary suspension and subsequent reinstatement of the gasoline sales tax in illinois and indiana following a price spike in 2000 earlier laws set the timing of the reinstatements providing plausibly exogenous changes in the tax rates using a unique dataset of daily prices at the gas station level 70 of the tax suspension is passed on to consumers in the form of lower prices while 80 100 of the tax reinstatements are passed on to consumers some evidence suggests that these short run pass through estimates are smaller near the state borders with the tax reinstatements associated with relatively higher prices up to an hour s drive into neighboring states

price matching and the domino effect in a retail gasoline market i introduction for many years there have been competition concerns regarding how retail gasoline prices are set in the united states and canada in several u s states including delaware maryland nevada and virginia such concerns gave rise to divorcement legislation under which refiners are not permitted to own or operate gas stations 1 concerns have also been raised in the united states regarding zone pricing a company that owns and operates gasoline stations might define price zones where prices for all its stations in the zone are the same it has been suggested that zone pricing is a form of price discrimination and thus is an indicator of market power it has also been argued that zone pricing can be used in an anticompetitive fashion to coordinate pricing and to deter entry through localized price cutting 2 in canada consumers have complained about the perceived uniformity of retail gas prices in some markets and the perception that retailers raise their prices at the same time consumers have also been troubled by the observation that retail gasoline prices in some markets rise faster than they fall 3 concerns have also been voiced regarding interjurisdictional differences in retail prices that do not appear to be cost based indicating to consumers that retail gasoline markets are not competitive 4 possibly in response to public concerns canada s gasoline industry has advanced a competitive theory of gasoline pricing to explain certain perceived features of gas pricing that lead to allegations of collusion or anticompetitive behavior under this theory it is assumed that gas is a homogeneous good consumers are willing to drive long distances to save small amounts of money on gas and prices are perfectly observable by consumers and nearby competitors based on these assumptions it is argued that intramarket prices tend to uniformity individual stations quickly match price changes by certain competitors and price changes pass through an entire market almost immediately in a domino fashion 5 while many complaints have been made regarding how retail gas prices are set and the gasoline industry has offered explanations there are almost no publicly available studies of how prices actually change in urban retail gasoline markets using complete station specific data on intraday price changes over a long period of time such data are simply not available for most urban markets and can only be collected through personal observation of prices or possibly via subpoena of retailers pricing records in the course of a formal investigation even here price data may not be complete yet without such data there exists no formal evidence that the stylized facts that the competitive theory attempts to explain are indeed facts and that pricing behavior is consistent with a theory of anti or procompetitive conduct the purpose of this article was to use gasoline station price data collected eight times per day for 103 d for 27 gas stations in guelph ontario to evaluate the accuracy of the received wisdom regarding gas prices and the implications advanced by the informal theory of competitive gas pricing while the informal competitive theory seems to have been accepted by governments in many instances some jurisdictions remain unconvinced for example the sense that consumers concerns regarding gasoline pricing were not being addressed led the house of legislative assembly of nova scotia to establish an all party committee to investigate gasoline pricing in that province in its report the committee made a number of strong recommendations such as retail divorcement or price regulation if divorcement is rejected a prohibition of petroleum product sales below acquisition cost and that refiners must charge the same rack price to all customers 6 these recommendations are clearly motivated by anxieties regarding possible anti competitive conduct which may or may not be supported by a detailed analysis of retail gasoline pricing data

exogeneity tests of market boundaries applied to petroleum products us antitrust law makes market definition and the calculation of marketshare statistics an integral part of the determination of the anticompetitive impact of a merger because markets frequently overlap however market definition is rarely an easy task a statistical test that can be used as an aid in defining markets is proposed here time series techniques are used to test if price in one region is exogenous to the process that determines price in another the rejection of exogeneity can be an indication that the two regions are economically linked and thus may belong to a common geographic market the test is applied to petroleumproduct prices from various regions of the united states time series techniques have long been appreciated by macroeconomists the uses to which they have been put range from testing for the exogeneity of variables used in the construction of macroeconomic models sims 1972 for example to discovering empirical regularities in macroeconomic data without imposing a priori structure on the observations ashenfelter and card 1982 for example in contrast these techniques have not been so

cointegration analysis of seasonal time series this paper reviews various recent approaches to cointegration analysis of seasonal time series in addition to the usual decisions concerning data transformations and univariate time series properties it is necessary to decide how seasonal variation is included in the multivariate model and how standard cointegration methods should accordingly be modified seasonal cointegration and periodic cointegration methods are discussed as are some of their recent refinements an overview of further research topics is also provided

assessing environmental economic and reliability impacts of flexible ramp products in miso s electricity market abstract increased variability and uncertainty of net electrical load due to high penetration of wind and solar power augments the need for dispatching conventional generators with sufficient ramping capability rc needed to balance demand with supply having sufficient rc reduces the need of last minute dispatch schedule modifications which cause cost reliability and environmental outcomes that reduce the benefits of renewables the midcontinent independent system operator miso has modified its unit commitment and economic dispatch algorithms to account for the economic value of provisioning adequate rc levels this paper explores the outcomes of this modified market clearing process by simulating 10 minute operations of a scaled miso test system for three representative months under low and high wind penetration scenarios changes in system performance are quantified by comparing system costs scarcity events pricing energy prices generation fuel mix wind power curtailment and co 2 emissions between the conventional market clearing algorithm and one with flexible rc products results indicate that adding rc products lowers co 2 emissions and system costs facilitates wind integration and improves reliability these benefits are robust to changes in the market clearing algorithm parameters such as over under generation penalties and reserve scarcity prices

health returns to modern heating evidence from china this study analyses the health effects of modern heating using china s centralized home heating infrastructure as a natural experiment the underlying health mechanism is that the recipients of mo

the seasonal cycle and the business cycle almost all recent research on macroeconomic fluctuations has worked with seasonally adjusted or annual data this paper takes a different approach by treating seasonal fluctuations as worthy of study in their own right our results show that seasonal fluctuations are an important source of variation in all macroeconomic quantity variables but are small or entirely absent in both real and nominal price variables the timing of the seasonal fluctuations consists of increases in the second and fourth quarters a large decrease in the first quarter and a mild decrease in the third quarter the paper demonstrates that with respect to each of several major stylized facts about business cycles the seasonal cycle displays the same characteristics as the business cycle in some cases even more dramatically than the business cycle that is we find that at seasonal frequencies as well as at business cycle frequencies output movements across broadly defined sectors move together the timing of production and the

firm based measurements of market power in transmission constrained electricity markets in this paper two different approaches to analyzing firm based market power considering transmission constraints are proposed one is an application of the transmission constrained residual demand jacobian while the other is a generalization of the residual supply index to the case of transmission constraints these two approaches provide complementary evaluations of market power medium and large scale system examples are provided to demonstrate computational efficiency and both approaches could be applied to real world electricity markets

can the u s ethanol industry compete in the alternative fuels market the u s ethanol fuel industry has experienced preferential treatment from federal and state governments ever since the energy tax act of 1978 exempted 10 ethanol gasoline blend gasohol from the federal excise tax combined with a 54c gal ethanol import tariff this exemption was designed to provide incentives for the establishment and development of a u s ethanol industry despite these tax exemptions until recently the u s ethanol fuel industry was unable to expand from a limited regional market ethanol was dominated in the market by mtbe methyl tertiary butyl ether only after mtbe was found to contaminate groundwater and consequently banned in many states did the demand for ethanol expand nationally limit pricing on the part of mtbe refiners is one hypothesis that may explain this lack of ethanol entry into the fuel additives market as a test of this hypothesis a structural vector autoregression svar model of the ethanol fuel market is developed the results support the hypothesis of limit pricing behavior on the part of mtbe refiners and suggest the u s corn based ethanol industry is vulnerable to limit price competition which could recur the dependence of the corn based ethanol price on supply determinants limits u s ethanol refiners ability to price compete with sugar cane based ethanol refiners without federal support u s ethanol refiners may find it difficult to compete with cheaper sugar cane refined ethanol chiefly from brazil

do gasoline mergers affect consumer prices the marathon ashland petroleum and ultramar diamond shamrock transaction abstract in 1999 marathon ashland petroleum map acquired the michigan assets of ultramar diamond shamrock uds which increased map s share of terminal storage in michigan from about 16 percent to about 25 percent and increased the share of gasoline stations bearing a map brand from about 16 percent to about 24 percent in this paper we examine whether this acquisition affected the retail price of gasoline we use a difference in differences model to compare price movements in six michigan cities affected by the acquisition with price movements in two nearby cities unaffected by the acquisition using this model we find no evidence that this acquisition led to higher prices for consumers

why do countries and industries with large seasonal cycles also have large business cycles we show that there is a strong positive correlation across countries and industries between the standard deviation of the seasonal component and the standard deviation of the nonseasonal component of aggregate variables after documenting this stylized fact we discuss possible explanations and develop a model that generates our empirical finding the main feature of the model is that firms endogenously choose their degree of technological flexibility as a function of the amounts of seasonal and nonseasonal variation in demand although this model is intended to be illustrative we find evidence supporting one of its key empirical implications

forecasting performance of seasonal dummy models relative to some alternatives abeysinghe economic letters 1991 36 175 197 journal of econometrics 1994 forthcoming showed that seasonal dummies in regressions may lead to spurious inference this paper evaluates the post sample forecasting performance of a seasonal dummy arima model with four other models the results in general do not stand in favor of the seasonal dummy approach

pollution havens and the trade in toxic chemicals evidence from u s trade flows national registries of toxic chemical emissions and facilities are increasingly used to raise public awareness of potential health hazards in local areas but an unintended consequence may be the offshoring of production to less regulated countries using disaggregated u s trade data this study examines the impact of registry listing on subsequent bilateral trade flows estimates from a difference in differences model indicate a significant shift toward imports from poorer countries following registry listing assuming that environmental protection is a normal good this result suggests the emergence of pollution havens due to more stringent u s environmental regulation

edgeworth price cycles evidence from the toronto retail gasoline market i exploit a new station level twelve hourly price dataset to examine the strong retail price cycles in the toronto gasoline market the cycles appear similar to theoretical edgeworth cycles strongly asymmetric tall rapid and highly synchronous across stations i test a series of predictions made by the theory about how firm behaviors would differentially evolve over the path of a cycle the evidence is consistent with the existence of edgeworth cycles and inconsistent with competing hypotheses while the cycles are an interesting phenomenon for study in their own right the evidence has important policy and welfare implications

do gasoline prices respond asymmetrically to crude oil price changes the authors test and confirm that retail gasoline prices respond more quickly to increases than to decreases in crude oil prices among the possible sources of this asymmetry are production inventory adjustment lags and market power of some sellers by analyzing price transmission at different points in the distribution chain the authors attempt to shed light on these theories spot prices for generic gasoline show asymmetry in responding to crude oil price changes which may reflect inventory adjustment effects asymmetry also appears in the response of retail prices to wholesale price changes possibly indicating short run market power among retailers

modelling seasonality in residential water demand the case of tunisia this article proposes to model seasonal patterns of residential water demand using the techniques of seasonal integration and cointegration the methodology is applied to quarterly aggregate time series data for tunisia 1980 2007 applying the same increasing multi step pricing scheme in the whole country first a seasonal cointegration analysis demonstrates the relevance of a pricing policy that increases the size of the lower consumption block in summer second the nonseasonal cointegration analysis reveals a relatively high price elasticity for the highest consumption block therefore we also propose to increase the tariff progressivity to promote water savings this modified pricing scheme will help to achieve goals of environmental protection and social equity

interfirm rivalry in a repeated game an empirical test of tacit collusion rivalry in the vancouver retail gasoline market is modeled as a repeated game service station demand cost and intertemporal reaction functions are estimated from daily data on individual station prices costs and sales these functions are then used to calculate noncooperative and cooperative solutions to the constitutent game and the actual outcome of the repeated game the actual outcome is found to be substantially less lucrative than the monopoly solution nevertheless all stations are better off than if they played their noncooperative strategies in every period copyright 1987 by blackwell publishing ltd

multitask agency and contract choice an empirical exploration the multitask agency problem is examined empirically using contracts between private integrated oil companies and their service stations in the city of vancouver the empirical tests assess how variations in the characteristics of one task affect the choice of agent compensation scheme for another comparative statics from the model predict that higher powered incentives will be offered for gasoline sales when the secondary activity is not highly complementary with gasoline retailing where complementarity is measured by the cross price demand effect the covariation in uncertainty and the degree of effort substitutability copyright 1996 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association

the role of exclusive territories in producers competition reprinted in cartels stephen salant ed the international library of critical writings in economics edward elgar reference collections

price controls and market structure evidence from gasoline retail markets in this paper we study the effect of price floor regulations on the organization and performance of markets the standard interpretation of the effects of these policies is concerned with short run market distortions associated with excess supply since price controls prevent markets from clearing they lead to higher prices while this analysis may be correct in the short run it does not consider the dynamic equilibrium consequences of price controls we demonstrate that price floor regulations can have important long run effects on the the structure of markets by crowding them and creating endogenous barriers to entry for low cost retailers moreover we show that these factors can indirectly lower productivity and possibly even prices we test this in the context of an actual regulation imposed in the retail gasoline market in the canadian province of quebec and show that the policy led to more competition between smaller less efficient stations this resulted in lowered sales and despite the reduction in efficiency did not increase prices

dynamic pricing in retail gasoline markets supergame models of tacit collusion show that supportable price cost margins increase with expected future collusive profits ceteris paribus as a result collusive margins will be larger when demand is expected to increase or marginal costs are expected to decline using panel data on sales volume and gasoline prices in 43 cities over 72 months we find behavior consistent with tacit collusion in retail gasoline markets controlling for current demand and cost current margins increase with expected next month demand and decrease with expected next month cost the results are not consistent with intertemporal l inkages due to inventory behavior or customer loyalty

spurious deterministic seasonality it is sometimes assumed that the r2 of a regression of a first order differenced time series on seasonal dummy variables reflects the amount of seasonal fluctuations that can be explained by deterministic variation in the series in this paper we show that neglecting the presence of seasonal unit roots may yield spuriously high values of this coefficient

taking the dogma out of econometrics structural modeling and credible inference without a doubt there has been a credibility revolution in applied econometrics one contributing development has been in the improvement and increased use in data analysis of structural methods that is the use of models based in economic theory structural modeling attempts to use data to identify the parameters of an underlying economic model based on models of individual choice or aggregate relations derived from them structural estimation has a long tradition in economics but better and larger data sets more powerful computers improved modeling methods faster computational techniques and new econometric methods such as those mentioned above have allowed researchers to make significant improvements while angrist and pischke extol the successes of empirical work that estimates treatment effects based on actual or quasi experiments they are much less sanguine about structural analysis and hold industrial organization up as an example where progress is less dramatic indeed reading their article one comes away with the impression that there is only a single way to conduct credible empirical analysis this seems to us a very narrow and dogmatic approach to empirical work credible analysis can come in many guises both structural and nonstructural and for some questions structural analysis offers important advantages in this comment we address the criticism of structural analysis and its use in industrial organization and consider why empirical analysis in industrial organization differs in such striking ways from that in fields such as labor which have recently emphasized the methods favored by angrist and pischke

tests of seasonal integration and cointegration in multivariate unobserved component models this paper considers tests of seasonal integration and cointegration for multivariate unobserved component models first the locally best invariant lbi test of the null hypothesis of a deterministic seasonal pattern against the alternative of seasonal integration is derived for a model with gaussian i i d disturbances and deterministic trend then the null hypothesis of seasonal cointegration is considered and a test for common nonstationary components at the seasonal frequencies is proposed the tests are subsequently generalized to account for stochastic trends weakly dependent errors and unattended unit roots asymptotic representations and critical values of the tests are provided while the finite sample performance is evaluated by monte carlo simulation experiments finally the tests are applied to the series of industrial production of the four largest countries of the european monetary union it is found that germany does not appear to cointegrate with the other countries at most seasonal frequencies while there seems to exist a common nonstationary seasonal component between france italy and spain copyright 2006 john wiley sons ltd

a treatment effect method for merger analysis with an application to parking prices in paris we propose a method of building control groups for retrospective merger evaluation the procedure involves two parameters a distance or radius and an order of exposure reflecting the notion that a merger can affect an outlet in a more or less direct way we implement the method of estimating the price effect of a merger in the paris parking market and illustrate the consequences of including indirectly exposed outlets in the control group the methodology applies to any industry with spatial competition and allows one to check the sensitivity of the results to the choice of the control group

price discrimination and retail configuration the hypothesis that price discrimination based on willingness to pay for quality can occur in multifirm markets is confirmed using microdata on gasoline retailing a test that discriminates between price structures associated with discrimination and with cost driven competitive differentials is developed and implemented with controls for variation in outlet and market characteristics a second test based on profitability variation rejects a competitive peak load pricing explanation for the observed price dispersion the data suggest that price discrimination at the retail level adds at least 9 a gallon to the average price of full service gasoline

consumer search and dynamic price dispersion an application to gasoline markets this article studies the role of imperfect information in explaining price dispersion we use a new panel data set on the u s retail gasoline industry and propose a new test of temporal price dispersion to establish the importance of consumer search we show that price rankings vary significantly over time however they are more stable among stations at the same street intersection weestablishtheequilibriumrelationshipsbetweenpricedispersionandkeyvariables from consumer search models price dispersion increases with the number of firms in the market decreases with the production cost and increases with search costs

do rockets rise faster and feathers fall slower in an atmosphere of local market power evidence from the retail gasoline market this study explores the possibility that local market power influences the observed asymmetric relationship between changes in wholesale gasoline costs and changes in retail gasoline prices i exploit an original data set of weekly gas station prices in southern california from september 2002 to may 2003 and take advantage of detailed station and local market level characteristics to determine the extent to which geographic and product differentiation influence price response asymmetry i find that brand identity proximity to rival stations and local market features and demographics each influence a station s predicted price response asymmetry

allocation of unit start up costs using cooperative game theory this paper discusses a three part generation offer strategy that enables generators to put in unbundled variable operating costs and fixed start up no load costs we then propose methods based on cost sharing axioms to allocate fixed start up no load costs among electricity consumers load retailers that take into account equity and rationality considerations we focus on the single period cost allocation first we apply three well known game theoretic axioms the core the nucleolus and the shapley value we discuss the relative merits and demerits of each criterion and also explore certain theoretical conditions for the existence of the core and the shapley value lying inside the core finally the multiperiod start up cost allocation problem is studied allocations based on individual periods vis a spl grave vis composite allocation for all periods are compared and contrasted numerical examples are used to illustrate all theoretical concepts

do auctions and forced divestitures increase competition evidence for retail gasoline markets to foster competition governments can intervene by auctioning licenses to operate or by imposing divestitures the dutch government has done exactly that organizing auctions to redistribute tenancy rights for highway gasoline stations and imposing divestitures of such stations on the four major companies we evaluate this policy experiment and find that the auctioning of licenses without an obligation to divest has no discernible effect on prices an obligation to divest lowers prices by 1 3 2 3 at divested sites moreover prices decrease by 0 9 1 2 at sites nearby this suggests that the observed price decreases are at least partly due to competitive spillovers

energy and reserve market designs with explicit consideration to lost opportunity costs the primary goal of this work is to investigate the basic energy and reserve dispatch optimization cooptimization in the setting of a pool based market of particular interest is the modeling of lost opportunity cost introduced by reserve allocation the authors derive the marginal costs of energy and reserves under a variety of market designs they also analyze existence algorithm and multiplicity of optimal solutions the results of this study are used to support the reserve market design and implementation in iso new england control area

spatial differentiation and vertical mergers in retail markets for gasoline this paper studies an empirical model of spatial competition applied to gasoline markets the main feature is to specify commuting paths as the locations of consumers in a hotelling style model as a result spatial differentiation depends in an intuitive way on the structure of the road network and the direction of traffic flows the model is estimated using panel data on the quebec city gasoline market and used to evaluate the consequences of a recent vertical merger difference in difference and counterfactual simulation methods are compared and the results to a large extent validate the assumptions of the demand model jel g34 l13 l42 l81 q41 r41

shell shocked the impact of foreign entry on the gasoline retail market in china abstract since joining the wto in 2001 restrictions on foreign entry into china s energy sector have been steadily reduced we investigate the impact of royal dutch shell s entry on the pricing behavior of three varieties of gasoline in the retail market of china using a difference in difference pairwise estimator we show that a year after entry the average absolute price differential of gasoline between two cities increased by around 1 4 before falling the following year in other words shell s entry caused prices to diverge but only for a short period of time the largest price effect was found for highly refined fuels in western cities similar results are found when we examine the effect of entry of the top four foreign retailers policy implications are discussed

from the cradle to the labor market the effect of birth weight on adult outcomes lower birth weight babies have worse outcomes both short run in terms of one year mortality rates and longer run in terms of educational attainment and earnings however recent research has called into question whether birth weight itself is important or whether it simply reflects other hard to measure characteristics by applying within twin techniques using an unusually rich dataset from norway we examine the effects of birth weight on both short run and long run outcomes for the same cohorts we find that birth weight does matter despite short run twin fixed effects estimates that are much smaller than ols estimates the effects on longer run outcomes such as adult height iq earnings and education are significant and similar in magnitude to ols estimates

selling costs and switching costs explaining retail gasoline margins recent theoretical work has shown that price discrimination can take place in imperfectly competitive as well as monopoly markets the persistence of higher retail margins on unleaded than on leaded gasoline during the 1980s suggests that discrimination may occur even in very competitive markets this article studies a number of cost based explanations for such gasoline pricing as well as the possibility of price discrimination the analysis indicates that gas stations discriminate against groups of customers who are less likely to switch to another station the conclusions highlight the influence of shopping or search costs on pricing decisions even in markets thought to be quite competitive

the spanish retail petroleum market new patterns of competition since the liberalization of the industry in this paper we study the recent development of the spanish automotive fuels market in the context of a long process of liberalization and competition our aims are twofold first to overview the market s current patterns of competition while taking into account the political structural and strategic aspects that have marked the industry s recent evolution second to study in depth one competitive strategy that nowadays significantly influences competition and final prices the vertical relationships between operators and service stations our analysis draws attention to several indicators that may demonstrate the success of the opening and liberalization process increased levels of competition have stimulated the sector s growth development and modernization and given national firms an excellent platform for competing with newcomers furthermore studying the vertical agreements has produced interesting results we have found that relative price differences among brands increase in line with perceived quality differences and that the vertical separation of refineries and retailers eases price competition in the final market the empirical evidence was backed up with a database of 4164 spanish service stations

transmission constrained inverse residual demand jacobian matrix in electricity markets a generation firm in an electricity market may own multiple generators located at multiple locations this paper generalizes the concept of transmission constrained residual demand from a single generator s perspective to that of a generation firm we calculate the derivative of a generation firm s inverse residual demand function i e the jacobian matrix based on a multi parameter sensitivity analysis of the optimal power flow solution and characterize some of its properties this jacobian matrix provides valuable information such as in characterizing a generation firm s profit maximizing strategy we apply the bundle newton method utilizing the jacobian matrix to find a generation firm s maximum profit the effectiveness and performance of the algorithm is demonstrated with the ieee 118 bus system example the jacobian matrix and the profit maximizing algorithm are helpful for market participants to bid into electricity markets and for market monitors to analyze firm based strategic behaviors

price dispersion and competition with differentiated sellers i measure price dispersion among differentiated retail gasoline sellers and study the relationship between dispersion and the local competitive environment significant price dispersion exists even after controlling for differences in station characteristics and price differences between sellers change frequently the extent of price dispersion is related to the density of local competition but this relationship varies significantly depending on the type of seller and the composition of its competitors these findings are consistent with interactions between seller and consumer heterogeneity that are not well understood in the existing price dispersion literature

energy and reserve dispatch in a multi zone electricity market competitive bidding for ancillary services a s in addition to bidding for energy is increasingly recognized as an important part of electricity markets in this paper an lp based approach is presented for solving the multi product i e energy and a s products multi zone area physical market dispatch problem the approach can explicitly represent various constraints such as reserve requirement constraints network security limits and sharing of constrained resource capacity e g maximum unit generation between energy and reserve the joint dispatch method which dispatches energy and reserve market concurrently is extended to allow inter zonal reserve trading in a multi zone competitive pool numerical examples are included to demonstrate the salient characteristics of the joint dispatch solution

inverse optimization for the recovery of market structure from market outcomes an application to the miso electricity market we propose an inverse optimization based methodology to determine market structure from commodity and transportation prices the methods are appropriate for locational marginal price based electricity markets where prices are shadow prices in the centralized optimization used to clear the market we apply the inverse optimization methodology to outcome data from the midcontinent iso electricity market miso and under noise free assumptions recover parameters of transmission and related constraints that are not revealed to market participants but explain the price variation we demonstrate and evaluate analytical uses of the recovered structure including reconstruction of the pricing mechanism and investigations of locational market power through the transmission constrained residual demand derivative prices generated from the reconstructed mechanism are highly correlated to actual miso prices under a wide variety of market conditions in a case study the residual demand derivative is shown to be corr

vancouver s gasoline price wars an empirical exercise in uncovering supergame strategies this paper uses a unique data set to determine which dynamic model of tacit collusion best describes behaviour in a particular industry the area investigated is a region of the vancouver british columbia retail gasoline market players are service station managers who compete daily firms choose price in each period using strategies that depend on prices chosen in the previous period periodically unanticipated demand shocks precipitate price wars when shocks occur the firms in the market must determine the new demand conditions and adjust their strategies from an econometric point of view slopes of intertemporal reaction functions are latent variables the resulting system of equations with time varying parameters is estimated via the kalman filter different repeated game oligopoly models correspond to different transition matrices for the latent variables the models can thus be assessed in terms of their power to explain firm behaviour in this market

the seasonal cycle in u s manufacturing abstract this paper examines the seasonal cycle in the manufacturing sector of the u s economy the most significant feature is a sharp slowdown in july we argue that this event is not easily explained by technology or preference shifts but instead results from synergies across economic agents

spatial competition with changing market institutions summary competition across space can be fundamentally altered by changes in market institutions we propose a framework that integrates market altering policy changes in the spatial analysis of competitive behavior and incorporates endogenous breaks in explanatory variables for spatial panel datasets this paper fills a gap in the literature between work focusing on spatial price responsiveness of agents and work on changes in market regulations that affect competition we apply the framework to an important current fishery management policy to explore how a change from aggregate to individual fishing quotas affects the spatial price responsiveness of fish processors copyright 2012 john wiley sons ltd

market foreclosure and vertical merger a case study of the vertical merger between turner broadcasting and time warner abstract we employ an event study methodology the event being the vertical merger between time warner and turner broadcasting distribution and programming respectively in the cable television industry we assess the effects of the merger on final prices subscriptions and carriage and marketing decisions of time warner the analysis finds several interesting facts first foreclosure in time warner markets following the merger is observed for the rival channels that are not integrated with any cable distributors second the turner broadcasting channels that increased market shares because of this merger appeared to be foreclosed by time warner prior to the merger the preference for own channels by time warner persisted despite a lower quality of channel bundles in its markets efficiency gains from the merger were not passed on to consumers

perfect competition urbanization and tax incidence in the retail gasoline market i introduction in applied tax incidence studies it is typically assumed that prices respond one for one to changes in sales and excise taxes chernick and reschovsky 1997 pechman 1985 shepard 1976 state of wisconsin department of revenue 2004 wiese rose and schluter 1995 zupnick 1975 is this assumption reasonable despite the fundamental role of tax incidence in the study of public finance there is surprisingly little empirical analysis that sheds light on who bears the burden of taxes in this article we examine the incidence of state gasoline excise taxes using monthly price data for all 50 states in the united states over the period 1984 1999 our estimation results generally indicate full shifting of gasoline taxes to the final consumer with changes in gasoline taxes fully reflected in the tax inclusive gasoline price almost instantly we also find that the incidence of excise taxes depends on the competitiveness of retail gasoline markets e g urban vs rural markets gasoline markets in urban states typically exhibit full shifting but those in rural states demonstrate somewhat less than full shifting although the issue of sales and excise tax incidence has received considerable attention over the years most research has focused on tax incidence theory and the standard conclusion of much of this theoretical analysis is that consumers bear the full burden of any sales and excise taxes 1 based primarily on this theoretical foundation most applied incidence studies assume that sales and excise taxes are fully reflected in consumer prices and the distribution of tax burdens across income classes necessarily reflects this assumption however actual empirical testing of this assumption of full forward shifting has been surprisingly sparse 2 in important recent research poterba 1996 and besley and rosen 1999 have conducted empirical analyses of the incidence of excise taxes poterba 1996 uses city specific clothing and personal care price data covering the 1947 1977 and the 1925 1939 periods to examine the degree to which state and local retail sales taxes are shifted to consumers with two data sets based on bureau of labor statistics bls city specific consumer price indices using these bls data on tax inclusive prices poterba 1996 constructs quarterly price indices for each of 28 standard metropolitan statistical areas smsas many of these 28 smsas experienced significant changes in sales tax rates and poterba 1996 uses these tax shocks to determine the incidence of sales taxes his estimation results are somewhat variable but in general he finds for the postwar period that taxes are fully shifted to consumers in some cases he finds limited evidence of overshifting although it is never possible to reject the null hypothesis that prices rise point for point with the changes in the tax and he also finds that full shifting typically though not always occurs in the first quarter of the tax change poterba 1996 also examines tax incidence for individual smsas during the depression era and his results indicate significant differences across metropolitan areas in the degree of tax shifting for example prices on women s clothing in chicago show significant overshifting but atlanta shows negative shifting a result that does not seem plausible besley and rosen 1999 also examine the incidence of sales taxes using price data for 12 narrowly defined commodities in 155 different u s cities using quarterly price data for the period 1982 1990 issued by the american chamber of commerce researchers association accra 3 they not only find full shifting for a number of commodities but also find overshifting for more than half the products a result they attribute to imperfect competition in the retail sector while this recent empirical research has significantly expanded our understanding of the actual nature of sales and excise tax incidence we believe that our work here on gasoline excise taxes makes several contributions to the empirical literature

empirical investigation of retail fuel pricing the impact of spatial interaction competition and territorial factors abstract this paper explores the determinants of fuel prices by proposing an empirical framework that integrates three kinds of influencing factors spatial interaction competition and territorial factors for competition we define a general variable the presence of competing stations within a radius and two specific variables the presence of low cost stations and the presence of same brand stations we proceed with a step wise adjustment of the radius by gradually increasing it to evaluate the spatial scope of different competition effects using data on prices of fuel stations in rome italy we estimate spatial econometric models that provide evidence of spatial dependence in price between stations we also find that competition affects prices but the relevance of its impact depends on radius length finally the territorial factors remarkably influence prices if these factors are introduced in the model the magnitude of spatial parameters weakens allowing to accurately assess the intensity of spatial dependence

a sensitivity approach to detection of local market power potential market power gives certain market participants the ability to manipulate the market to their advantage when their product is not substitutable by competitors identification of generators which have the potential for market power either individually or within a small group is performed using sensitivity information from the linear programming optimal power flow lp opf the impact of network constraints on admissible price perturbations are used to group generators that have the potential to exhibit local market power specific price perturbation vectors are found that highlight a constraint induced locational advantage for these suppliers in practice this is most commonly observed in load pockets for which iso policies mitigate market power

non convex costs and capital utilization a study of production scheduling at automobile assembly plants i study detailed data from eleven automobile assembly plants these data display considerable cross plant heterogeneity in production scheduling to explain the observed heterogeneity i solve a dynamic programming model when desired production is below the plant s minimum e cient scale non convexities induce production bunching the plant uses less than full capital utilization on average and production is more volatile than sales when desired production is above the plant s minimum e cient scale the plant operates in a convex region of the cost curve in this case it uses high levels of capital utilization and production is less volatile than sales 2000 elsevier science b v all rights reserved jel classixcation e23 d21 l23

evaluation of market rules using a multi agent system method the california energy crisis in 2000 2001 showed what could happen to an electricity market if it did not go through a comprehensive and rigorous testing before its implementation due to the complexity of the market structure strategic interaction between the participants and the underlying physics it is difficult to fully evaluate the implications of potential changes to market rules this paper presents a flexible and integrative method to assess market designs through agent based modeling realistic simulation scenarios are constructed for evaluation of the proposed pjm like market power mitigation rules of the california electricity market simulation results show that in the absence of market power mitigation generation company genco agents facilitated by q learning are able to exploit the market flaws and make significantly higher profits relative to the competitive benchmark the incorporation of pjm like local market power mitigation rules is shown to be effective in suppressing the exercise of market power