the expansion of modern agriculture and global biodiversity decline an integrated assessment the world is banking on a major increase in food production if the dietary needs and food preferences of an increasing and increasingly rich population are to be met this requires the further expansion of modern agriculture but modern agriculture rests on a small number of highly productive crops and its expansion has led to a significant loss of global biodiversity ecologists have shown that biodiversity loss results in lower plant productivity while agricultural economists have linked biodiversity loss on farms with increasing variability of crop yields and sometimes lower mean yields in this paper we consider the macro economic consequences of the continued expansion of particular forms of intensive modern agriculture with a focus on how the loss of biodiversity affects food production we employ a quantitative structurally estimated model of the global economy which jointly determines economic growth population and food demand agricultural innovations and land conversion we show that even small effects of agricultural expansion on productivity via biodiversity loss might be sufficient to warrant a moratorium on further land conversion

pareto improving campaign finance policy this paper argues that campaign finance policy in the form of contribution limits and matching public financing can be pareto improving even under very optimistic assumptions concerning the role of campaign advertising and the rationality of voters the optimistic assumptions are that candidates use campaign contributions to convey truthful information to voters about their qualifications for office and that voters update their beliefs rationally on the basis of the information they have seen the argument also assumes that campaign contributions are provided by interest groups and that candidates can offer to provide policy favors to attract higher contributions

viewpoint climate impacts on agriculture searching for keys under the streetlight abstract this paper provides a critical assessment of the literature estimating the consequences of climate impacts in agriculture and the food system this literature focuses overwhelmingly on the impact of elevated co2 concentrations in the atmosphere higher temperatures and changing precipitation on staple crop yields while critically important for food security we argue that researchers have gravitated to measuring impacts under the streetlight where data and models are plentiful we argue that prior work has largely neglected the vast majority of potential economic impacts of climate change on agriculture a broader view must extend the impacts analysis to inputs beyond land including the consequences of climate change for labor productivity as well as for purchased intermediate inputs largely overlooked is the impact of climate change on the rate of total factor productivity growth and the potential for more rapid depreciation of the underlying knowledge capital underpinning this key driver of agricultural output growth this broader view must also focus more attention on non staple crops which while less important from a caloric point of view are critically important in redressing current micronutrient deficiencies in many diets around the world the paper closes with numerical simulations that demonstrate the extent to which limited input and output coverage of climate impacts can lead to considerable underestimation of the consequences for food security and economic welfare of particular significance is the finding that humans in the humid tropics are likely more vulnerable to heat stress than are many of the well adapted crops such as rice by omitting the impact of heat stress on humans most studies of climate impacts greatly understate the welfare losses in the world s poorest economies

selling favors in the lab experiments on campaign finance reform campaign advertising can provide benefits to constituencies when used to fund the distribution of useful information but voters can be harmed if candidates finance such advertising by trading policy favors to special interests in exchange for contributions we report data from novel laboratory campaign finance experiments that shed light on this tradeoff and that provide rigorous empirical evidence on formal campaign finance theory our key finding is that voters respond to advertising differently between special interest and publicly financed campaigns and that the nature of this difference is qualitatively consistent with formal models predictions

the future of food demand understanding differences in global economic models understanding the capacity of agricultural systems to feed the world population under climate change requires projecting future food demand this article reviews demand modeling approaches from 10 global economic models participating in the agricultural model intercomparison and improvement project agmip we compare food demand projections in 2050 for various regions and agricultural products under harmonized scenarios of socioeconomic development climate change and bioenergy expansion in the reference scenario ssp2 food demand increases by 59 98 between 2005 and 2050 slightly higher than the most recent fao projection of 54 from 2005 2007 the range of results is large in particular for animal calories between 61 and 144 caused by differences in demand systems specifications and in income and price elasticities the results are more sensitive to socioeconomic assumptions than to climate change or bioenergy scenarios when considering a world with higher population and lower economic growth ssp3 consumption per capita drops on average by 9 for crops and 18 for livestock the maximum effect of climate change on calorie availability is 6 at the global level and the effect of biofuel production on calorie availability is even smaller

estimating the effect of campaign spending on senate election outcomes using instrumental variables o examine the traditional view that challenger spending is more effective than incumbent spending 7 i reestimate the effects of spending using instrumental variables that affect a candidate s ability to raise campaign funds such as candidate wealth levels hhen the endogeneity of candidate spending levels is properly taken into account the marginal effects of incumbent and challenger spending are roughly equal in contrast to previous research showing that because of higher marginal returns to challenger spending the incumbent s spending advantage cannot explain high incumbent reelection rates this article shows that in an average senate election the incumbent s spending advantage yields a 6 increase in the incumbent s vote share that incumbent spending wins elections has direct implications regarding the consequences of campaign finance reform my findings imply that equalizing spending levels may significantly increase incumbent defeat rates and caps on candidate spending may improve the chances of challengers in american congressional elections incumbents routinely win reelection even in the 1994 republican landslide change in the partisan makeup of congress occurred mainly through open seats switching from the democrats to the republicans a common explanation for high congressional reelection rates is the large campaign spending advantage enjoyed by incumbents it is widely believed that challenger spending is very important but there is surprisingly little evidence in the academic literature that incumbent campaign spending has an important effect on congressional election outcomes in light of the substantial effort incumbents devote to fundraising as well as some nagging methodological questions about existing academic studies the effect of incumbent spending on election outcomes remains an unresolved issue accurately measuring how incumbent spending leads to votes is of obvious importance politicians want to win elections and so if money matters then this will influence their behavior if campaign spending effects are trivial then concerns about politicians being

global land use implications of first and second generation biofuel targets recently an active debate has emerged around greenhouse gas emissions due to indirect land use change iluc of expanding agricultural areas dedicated to biofuel production in this paper we provide a detailed analysis of the iluc effect and further address the issues of deforestation irrigation water use and crop price increases due to expanding biofuel acreage we use globiom an economic partial equilibrium model of the global forest agriculture and biomass sectors with a bottom up representation of agricultural and forestry management practices the results indicate that second generation biofuel production fed by wood from sustainably managed existing forests would lead to a negative iluc factor meaning that overall emissions are 27 lower compared to the no biofuel scenario by 2030 the iluc factor of first generation biofuels global expansion is generally positive requiring some 25 years to be paid back by the ghg savings from the substitution of biofuels for conventional fuels second generation biofuels perform better also with respect to the other investigated criteria on the condition that they are not sourced from dedicated plantations directly competing for agricultural land if so then efficient first generation systems are preferable since no clear technology champion for all situations exists we would recommend targeting policy instruments directly at the positive and negative effects of biofuel production rather than at the production itself

introducing detailed land based mitigation measures into a computable general equilibrium model abstract we propose a new climate change mitigation assessment method focusing on agriculture forestry and land use change sectors by coupling the computable general equilibrium cge model with a bottom up type technology model the cge model covers the entire economic market but includes a rough description of mitigation measures whereas the bottom up type technology model takes into account abatement cost and mitigation effects of individual mitigation measures but only focuses on a few sectors the coupled framework enables us to connect relevant conditions and to complement the shortcomings of each model as a test we applied our method to indonesia which has set a national greenhouse gas emissions reduction target for 2020 a large proportion of indonesia s greenhouse gas emissions are from the land use sector we assessed the differences in modeling behaviors between the cge models with and without coupling the bottom up type model the two primary findings were 1 consumption loss estimated by the coupled cge 1 2 was larger than the loss estimated by the uncoupled model 0 5 because the emission reduction estimated by the bottom up model was less than the standalone cge s estimate and 2 consumption loss caused by achieving the reduction target by 2020 in indonesia strongly depends on the assumption of mitigation costs and available land area for the emission reduction measures

gordon tullock and experimental economics gordon tullock s research has substantially influenced the development of economic science in general and experimental economics in particular we present the first comprehensive survey of this significant achievement we show how tullock s research in bioeconomics influenced later developments in neuroeconomics and how his pioneering work on rent seeking generated a literature of laboratory tests of his hypothesis we also describe tullock s own experiments and draw attention to his early insights on trust games

the citizen candidate model an experimental analysis citizen candidate models represent a significant advance in the analysis of public choice they provide added realism to models of endogenous policy formation relate the number of candidates to the benefits and costs associated with electoral competition and support equilibria with differentiated candidate positions even with a multidimensional policy space in this paper experimental methods are utilized to test two of the model s equilibrium predictions the results support the prediction that an increase in the net benefits to winning an election increases the number of citizens entering electoral contests when the net benefits to winning an election are low the results support the prediction that the only candidate has the median preference further the results suggest that when net benefits are high two members of the electorate with preferences close to and symmetric about the median enter the election although convergence to this equilibrium takes time because entry is costly having multiple candidates lowers group payoffs and may be seen as inefficient

the causes of legal rents extraction evidence from spanish municipalities this paper analyzes the causes of legal political rent extraction by using a direct measure of it namely local top politicians wages in particular we investigate whether local politicians incentives to extract rents by setting their own wages are influenced by the degree of political competition and voter information we use a sample of the largest spanish municipalities over the years 2008 2010 the results indicate that weaker political competition and lesser voter information are related to more rent extraction in an additional analysis we show that higher wages do not ensure better financial management these findings confirm that when politicians can set their own salaries higher wages do not mean better management but they are just political rents

money and votes reconsidered congressional elections 1972 1982 the evolution of congressional campaign finance over the past decade is characterized by steady growth in campaign spending and other notable changes in campaign finance practices the main purpose of the research reported here was to determine whether these changes have altered the effects of campaign spending on election outcomes this required reexamination of auxiliary questions concerning how sending effects operate and can be measured it also required facing the limits of what analysis of aggregate campaign spending data can tell us about money in elections replication of ols and 2sls analyses of campaign spending effects produced solidly consistent results over the six congressional elections held between 1972 and 1982 taken at face value the evidence is overwhelming that the challenger s level of spending has a strong impact on the vote whereas that of the incumbent has virtually no impact at all but the evidence remains open to doubt on two grounds one is the probable inadequacy of the 2sls model or perhaps any possible model leaving the issue of simultaneity bias unsettled if bias remains the estimates exaggerate the electoral effects of the challenger s campaign expenditures the issue cannot be resolved with more of the same data but rather requires data of a different sort surveys taken over the course of a sample of campaigns would do the trick meanwhile i think it would be foolish to make policy on the assumption that bias is in fact substantial the greatest likelihood remains that restrictions on campaign money will have the general effect of hurting challengers jacobson 1979 the other doubtful albeit equally stable finding is that incumbents do not gain votes by spending in campaigns no incumbent seems to believe it and there is at least circumstantial evidence from for example the 1982 elections that their skepticism is quite justified if so the problem lies in the limits of what aggregate data of the kind analyzed here can tell us few incumbents do not spend heavily when they are strongly challenged if both candidates spend beyond the point needed to become thoroughly familiar to voters then the substance of the campaigns the contents of campaign messages become the dominant factors incumbents may need to spend money in order to change the message as new circumstances arise to frame new issues that would help them most or damage them least to win the battle of establishing the real issues like nonincumbents sitting members may sometimes need to spend beyond a certain threshold to remain competitive but nearly all of them do so when the necessity arises so aggregate spending data are largely uninformative how the money is spent rather than how much is what matters the two most notable developments in congressional campaign finance have opposing implications national party organizations particularly the republican have assumed an increasingly important role in financing campaigns greater central control leads to a more efficient distribution of the party s collective campaign resources which among other things promises to raise the overall level of electoral competition it also leads to more coordinated campaigning with greater emphasis on national themes and programs thus it should foster more cooperation and loyalty among fellow partisans in congress but pacs have also grown in numbers and in financial importance because most concentrate on gaining access to incumbents they do little to make elections more competitive because they usually pursue narrowly defined interests their influence fragments the congress and weakens party coalitions in this and other ways parties and pacs are natural rivals the most consequential decisions taken in the next round in campaign finance policy will be those which affect the relative importance of parties and pacs see u s congress 1984 for comments on this and other current campaign finance issues

an experimental study of alternative campaign finance systems transparency donations and policy choices we experimentally study the transparency effect of alternative campaign finance systems on donations election outcomes policy choices and welfare three alternatives are considered one where donors preferences and donations are unobserved by the candidate and public one where they are observed by the candidate but not the public and one where they are observed by all we label them full anonymity fa partial anonymity pa and no anonymity na respectively we find that in na and pa candidates consistently respond to donations by choosing policies favoring the donors fa in contrast is the most successful in limiting the influence of donations on policy choices donors benefit greatly from the possibility of donations whereas social welfare may be harmed in some treatments to our knowledge this article is the first to investigate the effect of different campaign finance systems distinguished by their transparency level jel d72

labor market effects of unemployment insurance design with the emergence of the great recession unemployment insurance ui is once again at the heart of the policy debate in this paper we review the recent theoretical and empirical evidence on the labor market effects of ui design we also discuss policy issues related to ui design including the structure of benefits the role of liquidity constraints and the pros and cons of a ui system in which the generosity of ui benefits is varying over the business cycle finally we identify potential areas of future research

media markets special interests and voters abstract this paper examines the role of mass media in countering special interest group influence i use the concentration of campaign contributions from political action committees to proxy for special interests capture of us senate candidates from 1980 to 2002 and compare the reaction of voters to increases in concentration in two different types of media markets in state media markets and out of state media markets unlike in state media markets out of state markets focus on neighboring states politics and elections thus if citizens punish political capture increases in concentration of special interest contributions to a particular candidate should reduce his vote share in in state counties relative to the out of state counties where the candidate receives less coverage i find that a one standard deviation increase in concentration of special interest contributions to incumbents reduces their vote share by about 0 5 to 1 5 percentage points in in state counties relative to the out of state counties robustness checks suggest that these results are not driven by omitted senator characteristics or by differences between in state and out of state counties along dimensions other than the media environment

why do global long term scenarios for agriculture differ an overview of the agmip global economic model intercomparison recent studies assessing plausible futures for agricultural markets and global food security have had contradictory outcomes to advance our understanding of the sources of the differences 10 global economic models that produce long term scenarios were asked to compare a reference scenario with alternate socioeconomic climate change and bioenergy scenarios using a common set of key drivers several key conclusions emerge from this exercise first for a comparison of scenario results to be meaningful a careful analysis of the interpretation of the relevant model variables is essential for instance the use of real world commodity prices differs widely across models and comparing the prices without accounting for their different meanings can lead to misleading results second results suggest that once some key assumptions are harmonized the variability in general trends across models declines but remains important for example given the common assumptions of the reference scenario models show average annual rates of changes of real global producer prices for agricultural products on average ranging between 0 4 and 0 7 between the 2005 base year and 2050 this compares to an average decline of real agricultural prices of 4 p a between the 1960s and the 2000s several other common trends are shown for example relating to key global growth areas for agricultural production and consumption third differences in basic model parameters such as income and price elasticities sometimes hidden in the way market behavior is modeled result in significant differences in the details fourth the analysis shows that agro economic modelers aiming to inform the agricultural and development policy debate require better data and analysis on both economic behavior and biophysical drivers more interdisciplinary modeling efforts are required to cross fertilize analyses at different scales

contrasting approaches to projecting long run global food security the provision of food has been a central preoccupation of policy makers throughout history today we are witnessing a period of food security pessimism triggered by increases in food prices and their higher volatility that began in 2008 however previous episodes of food pessimism were ended by the industrial and green revolutions and policy makers legitimately ask whether human ingenuity and technical advances will address today s worries without the need for their intervention here we explore some of the ways natural and social scientists have attempted to explore the supply and demand for food in the future to help policy makers understand the challenges ahead we are particularly struck that different communities have approached this problem in different ways that seldom reference each other we describe two broad approaches statistical extrapolation and economic simulation models of the food system that incorporate market mechanisms we compare the strengths and weaknesses of the different approaches and make some tentative suggestions about how they can together address important policy priorities

campaign finance and voter welfare with entrenched incumbents two candidates compete for elective office each candidate has information she would like to reveal to the voters but this requires costly advertising the candidates can solicit contributions from interest groups to finance such advertising these contributions are secured by promises to perform favors for the contributors should the candidate win the election voters understand this and elect the candidate they like best taking into account their expectations about promises to special interests there is an incumbency advantage in fundraising which is sometimes so great that the incumbent faces no serious opposition at all introducing partial public financing through matching funds improves voter welfare in districts that have advertising under the decentralized system while it can reduce welfare in other districts the optimal policy must strike a balance between these two effects

the market for congressional votes is timing of contributions everything this study utilizes the timing of campaign contributions to identify whether the objective of political action committees pacs is to influence congressional votes or solely to elect a preferred candidate the results show that pac behavior is consistent with an attempt to purchase congressional votes and to influence elections contributions increase in the weeks surrounding legislative events of importance to pacs and elections the magnitude of increased contributions is examined the article also addresses the lack of legal enforcement mechanisms in vote for contribution agreements it develops hypotheses regarding the timing of contributions as an inexpensive mechanism to assure contractual performance hypotheses are tested regarding pacs incentives to mitigate potential cheating by legislators on such agreements results show that pacs use the timing of contributions as a mechanism to prevent legislators from reneging on vote for contribution trades

agriculture and climate change in global scenarios why don t the models agree agriculture is unique among economic sectors in the nature of impacts from climate change the production activity that transforms inputs into agricultural outputs involves direct use of weather inputs temperature solar radiation available to the plant and precipitation previous studies of the impacts of climate change on agriculture have reported substantial differences in outcomes such as prices production and trade arising from differences in model inputs and model specification this article presents climate change results and underlying determinants from a model comparison exercise with 10 of the leading global economic models that include significant representation of agriculture by harmonizing key drivers that include climate change effects differences in model outcomes were reduced the particular choice of climate change drivers for this comparison activity results in large and negative productivity effects all models respond with higher prices producer behavior differs by model with some emphasizing area response and others yield response demand response is least important the differences reflect both differences in model specification and perspectives on the future the results from this study highlight the need to more fully compare the deep model parameters to generate a call for a combination of econometric and validation studies to narrow the degree of uncertainty and variability in these parameters and to move to monte carlo type simulations to better map the contours of economic uncertainty

a model of candidate location when one candidate has a valence advantage that under some fairly weak assumptions for all levels of the valence advantage the advantaged candidate chooses a more moderate position than the disadvantaged candidate empirical studies of congressional elections by fiorina 1973 and ansolabehere snyder and stewart 2001 support this result d owns 1957 seminal work presents a puzzle for scholars of u s elections why do candidates not converge to the median voter one of the best explanations is that the candidates themselves have ideological preferences as calvert 1985 and wittman 1977 1983 have shown when candidates have such preferences and they are sufficiently uncertain about the preferences of the median voter then they do not converge although they may moderate their positions from their ideal point the basic version of the calvert wittman model however does not account for another basic fact of u s elections often one of the candidates has an advantage due to a nonpolicy factor such as incumbency greater campaign funds better name recognition superior charisma superior intelligence and so on stokes has dubbed such factors valence factors and he has noted their importance in u s elections stokes 1963 1992 1 in this article i extend the basic calvert wittman model by giving one candidate a valence advantage over the other i show that if the valence characteristics of the candidates are approximately equal then when a candidate s valence advantage increases this causes her to move toward the

efficiency equity and timing of voting mechanisms we compare the behavior of voters under simultaneous and sequential voting rules when voting is costly and information is incomplete in many political institutions ranging from small committees to mass elections voting is sequential which allows some voters to know the choices of earlier voters for a stylized model we generate a variety of predictions about the relative efficiency and participation equity of these two systems which we test using controlled laboratory experiments most of the qualitative predictions are supported by the data but there are significant departures from the predicted equilibrium strategies in both the sequential and the simultaneous voting games we find a tradeoff between information aggregation efficiency and equity in sequential voting a sequential voting rule aggregates information better than simultaneous voting and is more efficient in some information environments but sequential voting is inequitable because early voters bear more participation costs

convergence of industry labor productivity among advanced economies 1963 1982 data are used for thirteen industrialized countries to investigate convergence of labor productivity levels in individual manufacturing industries over the 1963 82 period the authors find convergence in virtually every manufacturing industry among these countries the co efficient of variation of industry labor productivity declined in all but one of twenty eight industries however productivity convergenc e is stronger for all manufacturing than within individual industries especially heavy and high technology industries also variation in employment mix among countries plays little role in explaining cross country differences i n aggregate manufacturing productivity nor have changes in employment mixes been an important source of convergence copyright 1988 by mit press

interest groups campaign contributions and probabilistic voting this essay develops a simple model to analyze the impact of campaign contributions on electoral policy decisions of candidates for office interest groups here are firms that select contributions under the assumption that candidates policies and opposing groups donations remain unaltered candidates however recognize that their policy choices affect contributions campaign contributions are used by candidates to affect policy oriented voters perceptions of candidates positions in this framework the introduction of campaign contributions may affect candidates electoral policies and if they do then they benefit surely exactly one of the two interest groups

using repeat challengers to estimate the effect of campaign spending on election outcomes in the u s house previous studies of congressional spending have typically found a large positive effect of challenger spending but little evidence for effects of incumbent spending those studies however do not adequately control for inherent differences in vote getting ability across candidates high quality challengers are likely to receive a high fraction of the vote and have high campaign expenditures even if campaign spending has no impact on election outcomes to avoid that bias this paper examines elections in which the same two candidates face one another on more than one occasion differencing eliminates the influence of any fixed candidate or district attributes estimates of the effects of challenger spending are an order of magnitude below those of previous studies campaign spending has an extremely small impact on election outcomes regardless of who does the spending campaign spending limits appear socially desirable but public financing of campaigns does not

how changes in unemployment benefit duration affect the inflow into unemployment we study the effect of an unexpected reduction in maximum unemployment benefit duration on the inflow into unemployment of elderly workers in the netherlands we analyze the reduction as if it was a natural experiment finding substantial effects

unemployment insurance and moral hazard in employment abstract using the 1988 1990 lmas we examine whether the variable entrance requirement ver that claimants must work for a minimum number of weeks conditions job durations estimated employment hazards contain a large significant spike at the ver

comparing supply side specifications in models of global agriculture and the food system this article compares the theoretical and functional specification of production in partial equilibrium pe and computable general equilibrium cge models of the global agricultural and food system included in the agmip model comparison study the two model families differ in their scope partial versus economy wide and in how they represent technology and the behavior of supply and demand in markets the cge models are deep structural models in that they explicitly solve the maximization problem of consumers and producers assuming utility maximization and profit maximization with production cost functions that include all factor inputs the pe models divide into two groups on the supply side 1 shallow structural models which essentially specify area yield supply functions with no explicit maximization behavior and 2 deep structural models that provide a detailed activity analysis specification of technology and explicit optimizing behavior by producers while the models vary in their specifications of technology both within and between the pe and cge families we consider two stylized theoretical models to compare the behavior of crop yields and supply functions in cge models with their behavior in shallow structural pe models we find that the theoretical responsiveness of supply to changes in prices can be similar depending on parameter choices that define the behavior of implicit supply functions over the domain of applicability defined by the common scenarios used in the agmip comparisons in practice however the applied models are more complex and differ in their empirical sensitivity to variations in specification comparability of results given parameter choices is an empirical question to illustrate the issues sensitivity analysis is done with one global cge model magnet to indicate how the results vary with different specification of technical change and how they compare with the results from pe models

electoral competition and special interest politics have fixed positions on some issues but vary their positions on others in order to attract votes and campaign contributions in this context we examine whether special interest groups are governed by an electoral motive or an influence in their campaign giving and how their contributions affect the equilibrium platforms we show that each party is induced to behave as if it were maximizing a weighted sum of the aggregate welfares of informed voters and members of special interest groups the party that is expected to win a majority of seats caters more to the special interests

political competition with campaign contributions and informative advertising this paper presents a theory of political competition with campaign contributions and informative political advertising policy motivated parties compete by selecting candidates and interest groups provide contributions to enhance the electoral prospects of like minded candidates contributions are used to finance advertising campaigns that provide voters with information about candidates ideologies voters update their beliefs rationally given the information they have received the paper uses the theory to analyze the welfare economics of contribution limits such limits are shown to redistribute welfare from ordinary citizens to members of interest groups jel d72 h40

campaign advertising and voter welfare this paper investigates the role of campaign advertising and the opportunity of legal restrictions on it an electoral race is modeled as a signalling game with three classes of players many voters two candidates and one interest group the group has non verifiable insider information on the candidates quality and on the basis of this information offers a contribution to each candidate in exchange for a favorable policy position candidates spend the contributions they receive on non directly informative advertising this paper shows that 1 a separating equilibrium exists in which the group contributes to a candidate only if the insider information about that candidate is positive 2 although voters are fully rational a ban on campaign advertising can be welfare improving and 3 split contributions may arise in equilibrium and if they arise too often they are detrimental to voters

global models of trade in agriculture and related environmental modelling a review and assessment the continuing process of global integration bears implications for farmers and related supplying and processing industries in all parts of the world but also for the rest of the world economy an assessment of agricultural and trade policy impacts is bound to be complex and is often supported by quantitative modeling analysis this article provides an assessment of the present state of applied modelling in the area of trade and agricultural policies we provide in this paper a comparative assessment of alternative modelling approaches considering a total of 16 partial equilibrium and general equilibrium models the assessment includes theoretical modelling foundations datasets employed and institutional aspects such as model maintenance and dissemination of results a typology of models is provided by structuring the assessment along a clear set of evaluation criteria

contribution limits and transparency in a campaign finance experiment we experimentally compare electoral outcomes when donor contribution limits are varied the effect of contribution limits is studied under three levels of transparency one where donors preferences and donations are unobserved by the candidate and public one where they are observed by the candidate but not the public and one where they are observed by all we find that a combination of stricter contribution limits and full transparency is most successful at limiting donors influence on policy choice we also find that stricter contribution limits improve social welfare in some treatments we further find that the partial and no anonymity settings lead to centrist bias whereby implemented policies on average are more centrist than the candidate s preferences in most treatments

campaign spending with office seeking politicians rational voters and multiple lobbies abstract i introduce a microfounded model of campaign finance with office seeking politicians a continuum of voters and a large number of heterogeneous lobbies lobbies make contributions to politicians according to a common agency framework politicians use contributions to finance their electoral expenditures voters are not fooled by electoral expenditures they are influenced in a way that is consistent with the equilibrium behavior of lobbies and politicians the model is used to i determine the relation between campaign spending and the deviation from the median voter s preferred policy ii show the informational value of lobbies contributions iii evaluate the welfare implications of restricting campaign spending and iv interpret the empirical finding that campaign expenditures have a very low effect on election outcome although in equilibrium advertising provides voters with useful information under reasonable parameter values a ban on campaign contributions makes the median voter better off journal of economic literature classification numbers d72 d82 m37

electoral competition with informed and uninformed voters i present a model of electoral competition in which candidates raise campaign contributions by choosing policies that benefit interest groups and then expend those contributions to influence voters who are uninformed about the policies informed voters however vote based on those policies so candidates face a trade off between choosing a policy to generate funds to attract the uninformed vote and choosing a policy to attract the informed vote electoral equilibria are characterized for two categories of policies particularistic and collective in the case of particularistic policies the equilibrium policies of the candidates are separated if the proportion of uninformed voters is sufficiently high and the degree of separation is an increasing function of that proportion the model is extended to include the public financing of elections and incumbency advantages for the case of collective policies the candidates locate at the median of the ideal points of the informed voters and contributions are zero

impacts of increased bioenergy demand on global food markets an agmip economic model intercomparison integrated assessment studies have shown that meeting ambitious greenhouse gas mitigation targets will require substantial amounts of bioenergy as part of the future energy mix in the course of the agricultural model intercomparison and improvement project agmip five global agro economic models were used to analyze a future scenario with global demand for ligno cellulosic bioenergy rising to about 100 exajoule in 2050 from this exercise a tentative conclusion can be drawn that ambitious climate change mitigation need not drive up global food prices much if the extra land required for bioenergy production is accessible or if the feedstock for example from forests does not directly compete for agricultural land agricultural price effects across models by the year 2050 from high bioenergy demand in an ambitious mitigation scenario appear to be much smaller 5 average across models than from direct climate impacts on crop yields in a high emission scenario 25 average across models however potential future scarcities of water and nutrients policy induced restrictions on agricultural land expansion as well as potential welfare losses have not been specifically looked at in this exercise