habit formation interdependent preferences and demographic effects in the almost ideal demand system the authors model myopic habit formation interdependence of preferences among consumers and demographic effects as taste shifters in a micro consumer demand model of the almost ideal demand variety the model is estimated for dutch micro data the authors investigate the dynamic properties of the model and find that it behaves very differently from models without interdependence of preferences the implications for micro macro modeling are discussed copyright 1991 by royal economic society

sulfur dioxide control by electric utilities what are the gains from trade title iv of the 1990 clean air act amendments caaa established a market for transferable sulfur dioxide so2 emission allowances among electric utilities this market offers firms facing high marginal abatement costs the opportunity to purchase the right to emit so2 from firms with lower costs and this is expected to yield cost savings compared to a command and control approach to environmental regulation this paper uses econometrically estimated marginal abatement cost functions for power plants affected by title iv of the caaa to evaluate the performance of the so2 allowance market specifically we investigate whether the much heralded fall in the cost of abating so2 compared to original estimates can be attributed to allowance trading we demonstrate that for plants that use low sulfur coal to reduce so2 emissions technical change and the fall in prices of low sulfur coal have lowered marginal abatement cost curves by over 50 percent since 1985 the flexibility to take advantage of these chan

modeling regional economic dynamics spatial dependence spatial heterogeneity and nonlinearities abstract spatial modeling of economic phenomena requires the adoption of complex econometric tools which allow us to deal with important methodological issues such as spatial dependence spatial unobserved heterogeneity and nonlinearities in this paper we describe some recently developed econometric approaches i e spatial autoregressive semiparametric geoadditive models which address the three issues simultaneously we also illustrate the relative performance of these methods with an application to the case of house prices in the lucas county

livelihoods and poverty the role of migration a critical review of the migration literature this review of the literature concludes that development studies have paid insufficient attention to labour migration and makes a plea to integrate analyses of migration within those of agricultural and rural development it emphasises that population mobility is much more common than is often assumed and that this has been so throughout human history in fact available material suggests that it is as likely that population mobility has decreased as that it has increased a review of empirical studies shows that it may not be possible to generalise about the characteristics of migrants or about the effects of migration on broader development inequality or poverty the review concludes that given the importance of migration for the rural livelihoods of many people policies should be supportive of population mobility and possibilities should be explored to enhance the positive effects of migration

demand for sport this article reviews international literature on the demand for professional sport the first part presents a conceptual framework for understanding the sources and determinants of the demand for professional sporting contests the second part reviews empirical evidence on key determinants of attendance at sporting events and on other sources of demand such as broadcasting sponsorship and merchandising the review concludes that there is still much to be learned about demand for professional sport and that there are no simple lessons to be drawn from existing literature but important messages do emerge from studies of demand for attendance with regard to effects of uncertainty of outcome quality of contest and quality of viewing copyright 2003 oxford university press

access to capital and its impact on agrarian structure and productivity in kenya access to capital and its distribution across agents can profoundly shape the structure and performance of an agrarian market economy it is conceptually useful to distinguish between ex ante and ex post capital access ex ante capital access denotes the ability of agents to finance production costs e g labor and purchased inputs costs which must be paid ex ante that is prior to the actual realization of production ex post capital access that is access to capital after the realization of the production process is of particular importance as an insurance substitute in low income agrarian economies where contingency markets are imperfect buoyant ex post capital access would permit an individual to stabilize consumption year to year even as production fluctuates annually a number of theoretical models have ex

a policy agenda for pro poor agricultural growth abstract sub saharan africa and parts of south asia are likely to hold large numbers of very poor rural people into the foreseeable future although both history and theory suggest a pre eminent role for agricultural growth in poverty reduction in poor agrarian economies such growth today faces new difficulties many of these difficulties are endogenous to today s poor rural areas others result from broader processes of global change but some are due to changes in the dominant policy environment emphasizing liberalization and state withdrawal examination of 20th century green revolutions suggests that active state interventions were important in supporting critical stages of agricultural market development unfortunately such interventions benefits in institutional development are easily overlooked whereas their high costs are much more visible policy implications are discussed

transition in sub saharan africa agriculture urbanization and income growth abstract econometric analysis of some 40 years of data has provided mixed results because of the defects of the data and because there are some relatively sudden structural economic shifts an important shift is when agricultural labor ceases to grow now happening in sub saharan africa ssa a model of the interrelationship over time of the rural mainly agricultural sector and the urban mainly manufacturing and service sector is proposed each provides a market to the other growth in both requires investment but of distinctly different types their interaction results in an s shaped curve many ssa countries are in the acceleration phase and its agriculture particularly in semi arid areas is increasingly oriented to the growing home market case studies show farmers have invested and adopted new technologies but the transition to an urbanized economy has been hindered by poor policies the current need is for appropriate investments and policies to develop the productivity of the urban sectors so that they can continue to stimulate agriculture and provide jobs for those who are leaving farming

a virtuous circle model of rural urban development evidence from a kenyan small town and its hinterland using data from kenya this article explores several propositions of a virtuous circle model of rural urban development to determine when the model might operate within a local economy it is shown that the cycle of reinforcing linkages hinges on a vigorous export base external demand is only effective when farmers are connected to markets small towns help raise agricultural productivity by allowing farmers to spread risk by diversifying incomes vibrant agriculture spurs the proliferation of local non farm activities which in turn create demand for farm produce though not necessarily from the same area and finally the virtuous circle model can be undermined by inappropriate macroeconomic policies

investment and economic growth abstract the paper revisits the old question how much does investment contribute to economic growth building on recent work of maurice scott it suggests that the analysis of growth in developing as in the industrial countries would benefit from a capital accumulation approach in the following analysis economic growth is related to three variables all greatly influenced by the quality of economic policies the rate of investment the social rate of return to investment and the investment induced returns to labor

does the nonfarm economy offer pathways for upward mobility evidence from a panel data study in ethiopia summary empirical studies across many developing countries routinely document a positive correlation between participation in rural nonfarm employment and households wealth or income this paper explores whether nonfarm employment leads to higher consumption expenditure growth in ethiopia we find that 1 households consumption expenditure growth is positively correlated with the initial share of nonfarm income 2 the growth elasticity of nonfarm income share is higher for wealthier households and 3 the main source of growth for nonfarm participants comes from the higher rates of return participants enjoy on their human and physical capital

trading networks and liquidity provision abstract we study the profitability of traders in two fully electronic and highly liquid markets the dow and standard poor s 500 e mini futures markets using unique information that identify counterparties to a transaction we show and seek to explain the fact that the network pattern of trades captures the relations between behavior in the market and returns our approach includes a simple representation of how much a shock is amplified by the network and how widely it is transmitted this representation provides a possible shorthand for understanding the consequences of a fat finger trade a withdrawing of liquidity or other market shock

a reassessment of kenya s rural and urban informal sector abstract the nature and role of the so called informal sector are re examined on the basis of a detailed country study using different data sources relating to kenya which have recently been published or become available specific kenyan phenomena are identified and commented upon particularly the importance of divided households obtaining their living in both agriculture and the urban informal sector and the tendency of informal sector manufacturing enterprises to form agglomerations the informal sector is seen as a heterogeneous set of activities urban or rural which have the common features of catering not uniquely to the mass of low income consumers existing competitively due to the low supply price of labor and being capable of retaining an important role in economies with widely varying levels of development so long as this supply price remains low

why poor people get rich kenya 1960 1979 abstract this paper challenges the conventional model underlying much thinking on kenya which has stressed the extant inequality of assets including human capital and the presumed weakness of intersectoral links owing to structural rigidities in the system on the basis of recent survey data the authors test their hypothesis that the pattern of growth and distribution in the kenyan smallholder sector is best understood rather as being the outcome of the complex interaction of rural factor market failure and urban labour market participation the sources of growth may be distinguished as improved resource allocation capital formation and innovation so that the transmission mechanisms from factor market malfunctioning and urban employment onto growth and distribution must be via these three components the arguments which follow question the orthodox views on such phenomena as urban bias trickle down growth the functions of urban rural remittances and the need for land reform

latent homophily or social influence an empirical analysis of purchase within a social network consumers who are close to one another in a social network often make similar purchase decisions this similarity can result from latent homophily or social influence as well as common exogenous factors latent homophily means consumers who are connected to one another are likely to have similar characteristics and product preferences social influence refers to the ability of one consumer to directly influence another consumer s decision based upon their communication we present an empirical study of purchases of caller ring back tones using data from an asian mobile network that predicts consumers purchase timing and choice decisions we simultaneously measure latent homophily and social influence while also accounting for exogenous factors identification is achieved due to our dynamic panel data structure and the availability of detailed communication data we find strong influence effects and latent homophily effects in both the purchase timing and product choice decisions of consumers this paper was accepted by sandra slaughter information systems

inequality among equals embedding market and authority in league sports in league sports the regulatory authority of leagues is thought to counter market pressures that would otherwise concentrate player talent in smsas with the largest market potential the presumed opposition between authority and markets is not supported by league histories in the four major team sports these histories show that contrary to expectations market potential has the greatest influence on winning when league authority is formally strongest market potential has no influence on performance when league authority is opposed by antitrust law player unions rival leagues or league members to explain this anomaly authority and market relations must both be seen as embedded within the multiplex relations among team owners these relations changed dramatically with the rise of national audiences in the past three decades inequality among equals replaced inequality among unequals as the support of a rootless national audience replaced rooted and unequal local audiences altering the opportunity

a comment on investment and economic growth abstract anderson s recent paper 1990 makes use of what appears to be a conventional vintage model to analyze economic growth and gives estimated rates of return for a number of developing countries consistent with that model this type of model however implies that the rate of growth in the long run is independent of the share of investment in income a proposition which one suspects that many including anderson find unacceptable if contrary to convention one accepts that technical progress from one vintage to the next depends on investment one should change the way in which social rates of return are calculated and they will then usually be much higher than the rates anderson gives

ethnic capital and intergenerational mobility this paper analyzes the extent to which ethnic skill differentials are transmitted across generations i assume that ethnicity acts as an externality in the human capital accumulation process the skills of the next generation depend on parental inputs and on the quality of the ethnic environment in which parents make their investments or ethnic capital the empirical evidence reveals that the skills of today s generation depend not only on the skills of their parents but also on the average skills of the ethnic group in the parent s generation

the role of information and social interactions in retirement plan decisions evidence from a randomized experiment this paper analyzes a randomized experiment to shed light on the role of information and social interactions in employees decisions to enroll in a tax deferred account tda retirement plan within a large university the experiment encouraged a random sample of employees in a subset of departments to attend a benee ts information fair organized by the university by promising a monetary reward for attendance the experiment multiplied by more than e ve the attendance rate of these treated individuals relative to controls and tripled that of untreated individuals within departments where some individuals were treated tda enrollment e ve and eleven months after the fair was signie cantly higher in departments where some individuals were treated than in departments where nobody was treated however the effect on tda enrollment is almost as large for individuals in treated departments who did not receive the encouragement as for those who did we provide three interpretations differential treatment effects social network effects and motivational reward effects to account for these results

asset commonality debt maturity and systemic risk we develop a model in which asset commonality and short term debt of banks interact to generate excessive systemic risk banks swap assets to diversify their individual risk two asset structures arise in a clustered structure groups of banks hold common asset portfolios and default together in an unclustered structure defaults are more dispersed portfolio quality of individual banks is opaque but can be inferred by creditors from aggregate signals about bank solvency when bank debt is short term creditors do not roll over in response to adverse signals and all banks are ine ciently liquidated this information contagion is more likely under clustered asset structures in contrast when bank debt is long term welfare is the same under both asset structures

does risk sharing motivate interdealer trading we use unique data from the london stock exchange to test whether interdealer trade facilitates inventory risk sharing among dealers we develop a methodology that focuses on periods of extreme inventories inventory cycles we further distinguish between inventory cycles that are unanticipated and those that are anticipated because of worked orders the pattern of interdealer trade during inventory cycles matches theoretical predictions for the direction of trade and the inventories of trade counterparts we also show that london dealers receive higher trading revenues for taking larger positions

bargaining in the transfer market theory and evidence this paper examines the transfer market for association football players as operated in the english football league using transfer data for the 1990 91 season after describing the purposes and procedures involved in the transfer system together with the motives of the participants we apply two person bargaining theory to analyse the determination of transfer fees the data and estimation procedures are explained and the results reported and interpreted our analysis suggests that the nash bargaining theory captures the salient features of the bargaining process in the footballer s transfer market

examining the roots of educational demand the case supporting rural agrarian development abstract the effort to manage educational growth in kenya has relied heavily upon cost sharing curricular reform and private initiative the result has been an unrestrained expansion of educational opportunity at all levels the cost approaching 40 of the recurrent government budget is not sustainable this paper revives an old solution that has been fully considered in the dialogue regarding educational reform i e rural agrarian development because the vast majority of kenyans are dependent upon the land for their livelihood they have been forced by growing land scarcity to seek wage employment in turn education has become the prerequisite for such employment in order to moderate the demand for education the economic strategies of kenyan smallholders must be altered this can be done by increasing the efficiency of resource use in the ural areas and increasing access to land in addition to the current employment generation efforts

rural urban migration in economic development abstract this paper provides a review of the theoretical literature on rural urban migration in contemporary ldcs the paper begins with a brief discussion of the lewis model before going on to discuss the todaro and the harris todaro models and the large literature which these models have spawned the question of job search in the context of migration and the role of family members in migration decisions are considered next the paper then takes a closer look at the informal sector and also sets out alternative migration functions to the ones usually employed in the literature the paper concludes with a brief note on some of the important implications arising from our study

something to talk about social spillovers in movie consumption we exploit the randomness of weather and the relationship between weather and moviegoing to quantify social spillovers in movie consumption instrumenting for early viewership with plausibly exogenous weather shocks captured in lasso chosen instruments we find that shocks to opening weekend viewership are doubled over the following five weekends our estimated momentum arises almost exclusively at the local level and we find no evidence that it varies with either ex post movie quality or the precision of ex ante information about movie quality suggesting that the observed momentum is driven in part by a preference for shared experience and not only by social learning

team roster turnover and attendance in major league baseball empirical support is shown for the propositionthat sports fans prefer the composition of their home team to remain the same from season to season controlling for price income population team quality league year the stadium effects the regression results indicate that for each percentage point increase in the turnover of the composition of the team attendance will fall by about 0 7 the implications of this heretofore ignored tendency are briefly discussed

the social multiplier aggregate data is often used to make inferences about individual level behavior if there are social interactions in which one person s actions influence his neighbor s incentives or information then these inferences are inappropriate the presence of positive social interactions or strategic complementarities implies the existence of a social multiplier where aggregate relationships will overstate individual elasticities we present a brief model and then estimate the size of the social multiplier in three areas the impact of education on wages the impact of demographics on crime and group membership among dartmouth roommates in these contexts there is a significant social multiplier jel ho jo co

identification of endogenous social effects the reflection problem this paper examines the reflection problem that arises when a researcher observing the distribution of behaviour in a population tries to infer whether the average behaviour in some group influences the behaviour of the individuals that comprise the group it is found that inference is not possible unless the researcher has prior information specifying the compisition of reference groups if this information is available the prospects for inference depend critically on the population relationship between the variables defining reference groups and those directly affecting outcomes inference is difficult to implossible if these variables are functionally dependent or are statistically independent the prospects are better if the variables defining reference groups and those directly affecting outcomes are moderately related in the population

an epidemic model of investor behavior i test whether social influence affects individual investors trading and stock returns in each of the 20 most active stocks in finland over 9 years the number of owners in a municipality multiplied by the number of investors who do not own a stock a measure of the rate of transmission of diseases and rumors through social contact predicts individual investor trading i control for known determinants of trade including daily news and show that competing explanations for the relation are unlikely socially motivated trades predict stock returns and the effects are not reversed suggesting that individuals share useful information individuals susceptibility to social influence has declined during the period but the opportunities for social influence have increased

migration and food consumption patterns in ghana abstract this paper examines the link between migration and food consumption patterns in ghana which has a history of widespread migration and high levels of poverty data from 4130 households from the nationally representative 2005 2006 ghana living standards survey are used for the analysis since migrants self select into migration an instrumental variable approach is taken to analyze the relationship between migration and total food expenditures per capita food expenditures across a range of food categories and shares of food expenditures across these categories overall the results indicate that migration does not substantially affect total food expenditures per capita and has minimal noticeable effect on food expenditure patterns looking at results in different settings the analysis indicates that only in high migration regions does migration appear to increase overall food expenditures resulting in a shift towards the consumption of potentially less nutritious categories of food such as sugar and beverages and eating out of the home the results raise questions about the value of migration for improving the food consumption of migrant sending households

winning games versus winning championships the economics of fan interest and team performance championship prospects as distinct from game winning prospects may contribute to a fan s interest in a particular sports team if so then both season length and the structure of championship playoffs help determine the equilibrium allocation of playing skills across the teams of a league evidence from a regression analysis of team attendance in baseball indicates that ticket demand depends in part on perceived flag winning prospects several patterns in the winning percentages of league leaders in the major u s team sports are consistent with the perspective that championship considerations influence the allocation of playing skills

coaching team production coaching team production the actual function of managers is the subject of much debate using data on more than 3000 male college basketball players their coaches and their skill levels we find a positive and significant relation between our ability to replicate an individual coach s allocation of playing time across players and his winning percentage although this result does not answer the central question of just what it is that managers contribute the results do support the property rights paradigm managers are the employees of workers and more generally sports data can be used to help understand related economic processes where quantifiable measures of inputs and outputs are more costly to obtain what is meant by performance input energy initiative work attitude perspiration rate of exhaustion or output sometimes by inspecting a team member s input activity we can better judge his output effect it is not always the case that watching input activity is the only or best means of detecting measuring or monitoring output effects of each team member but in some cases it is a useful way i introduction a major tenet of the alchian demsetz 1972 representation of the firm is that managers are hired by workers to prevent shirking and malfeasance in their own ranks absent overseers individual workers bear only a fraction of the cost of shirking and hence everyone undersupplies labor relative to its opportunity cost in this world the managerial function is to monitor inputs and meter rewards thereby reducing the incentive to shirk and raising each worker s marginal productivity the more dependence there is in the marginal products of laborers the more important the role of management this view of supervision is simultaneously intuitively pleasing and difficult to quantify this paper investigates the role of management in a setting where indisputably there is team production intercollegiate basketball 1 data on 3012 college basketball players across ten years and sixty five teams are used to replicate one aspect of coaching the allocation of playing time next we attempt to link coaching decisions to winning the goal is to determine if coaches who manage well by our standards are successful section ii motivates the paper in section iii the empirical methodology is detailed the monitoring function is estimated and related to coaching success section iv contains a summary and conclusion ii coaching decisions the essence of team production is interdependence and the inherent immeasurability of marginal productivity across workers however this does not mean that proxies for marginal productivity cannot be developed managers monitor worker inputs and deduce marginal products accordingly of course some inputs are more cheaply quantified than others attitude is hard to measure but heart rate is easy sweat is observed cheaply but workers can feign exhaustion in the famous chinese boatpullers fable the coxswain uses his whip to insure that coolies pull efficiently to persuade each worker to give the appropriate effort 2 mcmanus 1975 341 relates a story told by cheung boats are pulled upstream by a team of coolies prodded by an overseer with a whip an american lady horrified at the sight of the overseer whipping the men as they strained at their harness demanded that something be done about the brutality she was quickly informed those men own the rights to draw boats over this stretch of water and they have hired the overseer and given him his duties here the monitor uses his vision intuition and experience to determine shirking counseling the loafers with his whip but employing subjective observation is just one way to monitor

a note on soil depth failing markets and agricultural pricing abstract due to implementation of structural adjustment programs prices of agricultural products have increased in many developing countries from an environmental point of view it is an open question whether these price increases stimulate sustainable agriculture in the context of a simple model that includes labour intensive investments in soil conservation it is demonstrated that rising prices for agricultural outputs unambiguously increase soil conservation in the steady state with imperfect labour markets the reverse effect may occur giving rise to a conflict between agricultural reform programs and soil conservation

migrant remittances and physical investment purchases evidence from kenyan households this paper investigates the impact of remittances on household decisions to purchase physical investments in kenya using household survey data an instrumental variables approach is employed using rainfall variation and mobile network coverage as instruments to control for the endogeneity of remittances the empirical evidence obtained is suggestive of remittances having a positive and significant effect on the decisions by households to purchase physical investments

the peculiar externalities of professional team sports the economics literature has long been divided regarding whether competing sports teams can achieve the same efficient allocation of playing skills that a revenue maximizing league monopolist would choose despite the external effects the teams impose on each other in their pursuit of athletic talent in this article an explicit consideration of the arbitrage incentives that underlie the marketing and pricing of playing skills indicates that decentralized franchises generally fail to allocate talent efficiently for fans concerned about the championship prospects of their preferred team the popular complaint has merit big city teams win too much jel l83 i introduction twenty years before the end of major league baseball s comprehensive reserve clause which assigned to team owners the exclusive right to market player contracts simon rottenberg 1956 p 255 observed that a market in which freedom is limited by the reserve rule such as that which governs the baseball labor market distributes players among teams about as a free market would the subsequent economics literature has been divided regarding whether the distribution of players under the reserve clause and free agency is not just identical but also efficient my analysis suggests that it is not the typical popular view is that competitive balance is achieved when teams at least over time perform equally well as measured by winning percentage or championship frequency economic analysis suggests instead that if team revenues uniformly reflect fan satisfaction then competitive balance is optimal when talent is allocated so as to maximize revenues for the league as a whole the two notions of competitive balance match only when team markets are of equal size either by coincidence or because of freedom of entry and relocation of team franchises under the prevailing circumstances in which market sizes differ superior on field performance by large market teams does not in itself indicate to economists that the existing level of competitive balance is suboptimal the question of interest is whether the dominance of large market teams is excessive thereby reducing total league revenues the next section reviews the debate about the efficiency consequences that result from the external effects that teams impose on each other through their competition for athletic talent the following sections then establish three key points section iii shows that teams generally fail to achieve the league revenue maximizing allocation of talent when the teams acquire players from an external market with a perfectly elastic supply of playing skills section iv turns to the internal marketing of athletic talent for which quirk and el hodiri 1974 have demonstrated that decentralized franchises reach the same allocation of playing skills as a league revenue maximizing monopolist as long as internally marketed skills sell for a uniform price however the analysis of section iv indicates that the arbitrage process that drives the internal marketing of talent does not lead to a uniform price for playing skills but only to an equilibrium set of bilateral transaction prices between each pair of teams as a result decentralized franchises do not end up with an equal marginal revenue product of playing skills across teams and therefore do not achieve the allocation of talent that a league revenue maximizing monopolist would choose section v examines the nature of the discrepancy between the optimal allocation of talent and the allocation achieved by noncooperative franchises linking fan interest to the championship prospects of the fan s preferred team generates an outcome in which unrestricted competition for playing skills by decentralized franchises results in excessive domination by large market teams whose incremental acquisitions of playing skills impose negative externalities on third party rivals appropriate per unit taxes and or subsidies on playing skills can be structured as a first best policy to address this inefficiency

attendance at australian rules football a panel study the demand for australian rules football is examined using data on attendance at individual matches played between 1981 and 1986 an estimation methodology which is appropriate for a dynamic model with panel data is adopted and it is found that attendance at football is price inelastic and an inferior good the effect of habit in consumption behaviour stadium size uncertainty of outcome and team success are also shown to be important determinants of attendance

africa s economic performance limitations of the current consensus historical and micro survey evidence as well as the standard data from international organizations support less pessimistic conclusions on africa s development performance than those reached by many social scientists the changes that have benefited women over the last four decades are highlighted a discussion of growth in agricultural production follows however the complexity and the brutality of processes of social and economic change in sub saharan african economies are also stressed the theoretical implications of these complexities have not been adequately analyzed by world bank economists the bank s recent efforts to reassess its policies are therefore unlikely to achieve the results anticipated

malthus controverted the role of capital and technology in growth and environment recovery in kenya abstract investment in technological improvements coupled with management innovations and skills are commonly held to lead to growth rates which outpace population growth although this applies to both industry and agriculture anderson 1990 typical farm surveys in developing countries neglect to analyze fixed investments or the quality of management this paper provides a nonmathematical case study and model from kenya of the way in which investments in technological change and especially in land improvement have enabled rural incomes per capita to grow substantially with improved environmental conservation through the interactions of increased population density improved information and market opportunities population density and investment are shown to be critical interrelated factors investments require maintenance expenditures these are included in social cost benefit analysis but it is not always realized that labor on maintenance may have a rising opportunity cost which farmers take into account when selecting technologies although the major part of expenditures are made and managed by farmers government investments to stimulate and complement them are required as on the farm this requires wise management of recurrent and maintenance costs if the benefits of investment are to be lasting

sport as business there is both a popular and academic literature suggesting that owners of sports teams do not profit maximize the alternative formulation entails either win or utility maximization usually subject to a breakeven constraint another line of economic analysis holds that team owners do fundamentally profit maximize or that profit maximization provides a useful benchmark against which to assess actual performance there has been some empirical work attempting to decipher the true objective function of team owners these results are inconclusive objective functions however remain important because they affect both owner behaviour and league performance in practice owners objectives vary by team league and country and are strongly affected by how the team relates to an owner s other assets the next task for modelling the behaviour and performance of sports leagues is to take fuller account of the diversity of ownership objectives within a given league copyright 2003 oxford university press

modelling loss of resilience in agroecosystems rangelands in botswana economists have recently begun to consider the questions raised by the ecological concept of resilience a measure of the degree to which a system can be perturbed before it switches from one stability domain to another at a theoretical level it has been argued that the loss of resilience in an ecological economic system involves a change in its long run productive potential but no consideration has yet been given to the empirical investigation of this this paper discusses an econometric approach to the problem using the example of semi arid rangelands the long run productive potential of the system is regarded as an unobserved state variable change in which is irreversible or at least only slowly reversible it is estimated by applying the extended nonlinear kalman filter the paper illustrates the approach using data from botswana for the period 1965 1993 the maximum likelihood estimates of the parameters associated with the loss of resilience mechanism are non zero they indicate a small loss of resilience event at the end of the long drought in the 1980s however these parameters are very imprecisely estimated and are therefore statistically insignificant we find that the sensitivity of the system to exogenous shocks varies with fluctuations in both economic and non economic parameters contrary to what is usually thought to be the case the sensitivity of the system to exogenous shocks is only weakly affected by variations in offtake prices but is very strongly affected by variations in the cost of herd maintenance this suggests that offtake prices may be a weak tool for controlling the size of cattle stocks and preventing a loss of resilience on the other hand taxes on cattle stocks or grazing fees may be very effective