commodity price shocks and civil conflict evidence from colombia how do income shocks aect armed con ict theory suggests two op posite eects if labor is used to appropriate resources violently higher wages may lower con ict by reducing labor supplied to appropriation this is the opportunity cost eect alternatively a rise in contestable income may increase violence by raising gains from appropriation this is the rapacity eect our paper exploits exogenous price shocks in inter national commodity markets and a rich dataset on civil war in colombia to assess how dierent income shocks aect con ict we examine changes in the price of agricultural goods which are labor intensive and natural resources which are capital intensive we focus on coee and oil the two largest exports we nd that a sharp fall in coee prices in the 1990s increased violence dierentially in regions growing more coee by lower ing wages and the opportunity cost of joining armed groups in contrast a rise in oil prices increased violence dierentially in the oil region by in creasing municipal revenue siphoned through rapacity this pattern holds in several other agricultural and natural resource sectors providing robust evidence that price shocks aect con ict in opposite directions depending on the factor intensity of the commodity

learning about a new technology pineapple in ghana this paper investigates the role of social learning in the diffusion of a new agri cultural technology in ghana we use unique data on farmers communication patterns to define each individual s information neighborhood conditional on many potentially confounding variables we find evidence that farmers adjust their inputs to align with those of their information neighbors who were surpris ingly successful in previous periods the relationship of these input adjustments to experience further indicates the presence of social learning in addition applying the same method to input choices for another crop of known technol ogy correctly indicates an absence of social learning effects jel d83 013 033 q16

regulation profitability and diffusion of photovoltaic grid connected systems a comparative analysis of germany and spain abstract although both germany and spain were pioneers in the support and adoption of photovoltaics pv through feed in tariffs fits germany is the world s leading country in terms of installed pv capacity per capita and remains on a path of pv growth while the spanish pv market is virtually paralysed we analyse the divergent performance in both countries by reviewing the evolution of fits and by analysing the profitability of different types of installations for the period 2004 2014 while in germany the policies profitability and diffusion of pv were relatively stable over time in spain erratic policy changes and the distortionary effect of the solar orchard ownership structure caused a diffusion bubble june 2007 september 2008 and a subsequent profitability bubble 2009 2011 these bubbles led to the collapse of the support system in 2012 revealing the difficulty inherent in designing innovation and diffusion policies in the context of high uncertainty and rapid technological change

an innovation focused roadmap for a sustainable global photovoltaic industry the solar photovoltaic pv industry has undergone a dramatic evolution over the past decade growing at an average rate of 48 percent per year to a global market size of 31 gw in 2012 and with the price of crystalline silicon pv module as low as 0 72 w in september 2013 to examine this evolution we built a comprehensive dataset from 2000 to 2012 for the pv industries in the united states china japan and germany which we used to develop a model to explain the dynamics among innovation manufacturing and market a two factor learning curve model is constructed to make explicit the effect of innovation from economies of scale the past explosive growth has resulted in an oversupply problem which is undermining the effectiveness of demand pull policies that could otherwise spur innovation to strengthen the industry we find that a policy shift is needed to balance the excitement and focus on market forces with a larger commitment to research and development funding we use this work to form a set of recommendations and a roadmap that will enable a next wave of innovation and thus sustainable growth of the pv industry into a mainstay of the global energy economy

on the electrification of road transport learning rates and price forecasts for hybrid electric and battery electric vehicles abstract hybrid electric vehicles hevs and battery electric vehicles bevs are currently more expensive than conventional passenger cars but may become cheaper due to technological learning here we obtain insight into the prospects of future price decline by establishing ex post learning rates for hevs and ex ante price forecasts for hevs and bevs since 1997 hevs have shown a robust decline in their price and price differential at learning rates of 7 2 and 23 5 respectively by 2010 hevs were only 31 22 2010 kw 1 more expensive than conventional cars mass produced bevs are currently introduced into the market at prices of 479 171 2010 kw 1 which is 285 213 2010 kw 1 and 316 209 2010 kw 1 more expensive than hevs and conventional cars our forecast suggests that price breakeven with these vehicles may only be achieved by 2026 and 2032 when 50 and 80 million bevs respectively would have been produced worldwide we estimate that bevs may require until then global learning investments of 100 150 billion which is less than the global subsidies for fossil fuel consumption paid in 2009 these findings suggest that hevs including plug in hevs could become the dominant vehicle technology in the next two decades while bevs may require long term policy support

evaluating interval forecasts a complete theory for evaluating interval forecasts has not been worked out to date most of the literature implicitly assumes homoskedastic errors even when this is clearly violated and proceed by merely testing for correct unconditional coverage consequently i set out to build a consistent framework for conditional interval forecast evaluation which is crucial when higher order moment dynamics are present the new methodology is demonstrated in an application to the exchange rate forecasting procedures advocated in risk management

value at risk versus expected shortfall a practical perspective value at risk var has become a standard risk measure for financial risk management however many authors claim that there are several conceptual problems with var among these problems an important one is that var disregards any loss beyond the var level we call this problem the tail risk in this paper we illustrate how the tail risk of var can cause serious problems in certain cases cases in which expected shortfall can serve more aptly in its place we discuss two cases concentrated credit portfolio and foreign exchange rates under market stress we show that expected shortfall requires a larger sample size than var to provide the same level of accuracy 2004 elsevier b v all rights reserved

social networks and technology adoption in northern mozambique despite their potentially strong impact on poverty agricultural innovations are often adopted slowly using a unique household dataset on sunflower adoption in mozambique we analyse whether and how individual adoption decisions depend upon the choices of others in the same social networks since farmers anticipate that they will share information with others we expect farmers to be more likely to adopt when they know many other adopters dynamic considerations however suggest that farmers who know many adopters might strategically delay adoption to free ride on the information gathered by others we present empirical evidence that shows that the relationship between the probability of adoption and the number of known adopters is shaped as an inverse u in line with information sharing the network effect is stronger for farmers who report discussing agriculture with others the data contains information which is needed to ameliorate the identification issues that commonly arise in this context in particular social networks are precisely identified and in addition we can control for village heterogeneity and endogenous group formation

forecasting portfolio value at risk with nonparametric lower tail dependence estimates abstract we propose to forecast the value at risk of bivariate portfolios using copulas which are calibrated on the basis of nonparametric sample estimates of the coefficient of lower tail dependence we compare our proposed method to a conventional copula garch model where the parameter of a clayton copula is estimated via canonical maximum likelihood the superiority of our proposed model is exemplified by analyzing a data sample of nine different bivariate and one nine dimensional financial portfolio a comparison of the out of sample forecasting accuracy of both models confirms that our model yields economically significantly better value at risk forecasts than the competing parametric calibration strategy

backtesting expected shortfall accounting for tail risk the basel committee on banking supervision bis has recently sanctioned expected shortfall es as the market risk measure to be used for banking regulatory purposes replacing the well known value at risk var this change is motivated by the appealing theoretical properties of es as a measure of risk and the poor properties of var in particular var fails to control for tail risk in this transition the major challenge faced by financial institutions is the unavailability of simple tools for evaluation of es forecasts i e backtesting es the main purpose of this paper is to propose such tools specifically we propose backtests for es based on cumulative violations which are the natural analogue of the commonly used backtests for var we establish the asymptotic properties of the tests and investigate their finite sample performance through some monte carlo simulations an empirical application to three major stock indexes shows that var is generally unresponsive to extreme events such as those experienced during the recent financial crisis whereas es provides a more accurate description of the risk involved this paper was accepted by neng wang finance

capture and governance at local and national levels 135 despite the importance of this issue not much systematic research appears to have been devoted to assessing the relative susceptibility of national and local governments to interestgroup capture here we describe a model of two party electoral competition with probabilistic voting behavior and lobbying by specialinterest groups based on david baron 1994 and gene grossman and elhanan helpman 1996 that helps identify determinants of relative capture at different levels of government these include relative levels of voter awareness and interest group cohesiveness electoral uncertainty electoral competition heterogeneity of districts with respect to inequality and the electoral system while some of these uphold the traditional madisonian presumption others are likely to create a tendency for lower capture at the local level so the net effect is theoretically ambiguous this suggests that the extent of relative capture may be context specific and needs to be assessed empirically

risk sharing networks and insurance against illness most risk sharing tests on developing country data are conducted at the level of the village generally the full risk sharing hypothesis is rejected this paper uses detailed data on all insurance networks within a village in tanzania networks are not clustered but largely overlapping we test whether full risk sharing occurs within these networks while village level full insurance cannot be rejected for food consumption we find evidence consistent with at least partial insurance of non food consumption via networks

relationships and growth on the dynamic interplay between relational contracts and competitive markets in economic development this paper presents a dynamic general equilibrium model to investigate how different contracting modes based on formal and relational enforcements emerge endogenously and are linked dynamically with the process of economic development formal contracts are enforced by third party institutions courts whereas relational contracts are self enforcing agreements without third party involvement the novel feature of our model is that it demonstrates the co evolution of these different enforcement modes and market equilibrium conditions all of which are jointly determined we then characterise the equilibrium paths of such dynamic processes and show the time structure of relational contracting in the process of development in particular we show that relational contracting fosters the emergence of a market based economy in the growth phase of development however its role declines as the economy enters a mature phase

who gets the job referral evidence from a social networks experiment we use recruitment into a laboratory experiment in kolkata india to analyze how job networks select individuals for employment opportunities we present evidence that individuals face a tradeoff between choosing the most qualified individual for the job and the individual who is ideal from the perspective of their social network the experiment allows randomly selected subjects to refer members of their social networks to subsequent rounds of the experiment and varies the incentive schemes offered to these participants we find that when faced with performance pay individuals are more likely to refer co workers and less likely to refer family members high ability participants who are offered performance pay recruit referrals who perform significantly better on a cognitive ability task and also prove to be more reliable as evidenced by their choices in the trust game and performance on an effort task

informal insurance arrangements with limited commitment theory and evidence from village economies recent work on consumption allocations in village economies finds that idiosyncratic variation in consumption is systematically related to idiosyncratic variation in income thus rejecting the hypothesis of full risk pooling we attempt to explain these observations by adding limited commitment as an impediment to risk pooling we provide a general dynamic model and completely characterise efficient informal insurance arrangements constrained by limited commitment and test the model using data from three indian villages we find that the model can fully explain the dynamic response of consumption to income but that it fails to explain the distribution of consumption across households

credit markets in northern nigeria credit as insurance in a rural economy this article addresses the issues of imcomplete markets and imperfect information in the context of credit markets in rural northern nigeria in much recent theoretical literature the problems of moral hazard and adverse selection are assumed to be decisive for the organization of agrarian institutions in contrast it is found that in the four villages surveyed credit transactions take advantage of the free flow of information within rural communities information asymmetries between borrower and lender are unimportant and their institutional consequences the use of collateral and interlinked contracts are absent credit transactions play a direct role in pooling risk between households through the use of contracts in which the repayment owed by the borrower depends on the realization of random production shocks by both the borrower and the lender

an economic perspective on experience curves and dynamic economies in renewable energy technologies this paper analyzes dynamic economies in renewable energy technologies the paper has two contributions the first is to test the robustness of experience in solar photovoltaic solar thermal and wind energy to the addition of an explicit time trend which has been done in experience studies for other industries but not for renewable energy technologies estimation is carried out on the assumption that cumulative capacity industry production average firm production and electricity generation affect experience and thus the fall in price the second contribution is to test the impact of r d on price reduction in general cumulative experience is found to be highly statistically significant when estimated alone and highly statistically insignificant when time is added to the model the effect of r d is small and statistically significant in solar photovoltaic technology and statistically insignificant in solar thermal and wind technologies

targeting the poor evidence from a field experiment in indonesia the brief summarizes the targeting the poor evidence from a field experiment in indonesia for the period december 2008 january 2009 this paper reports an experiment in 640 indonesian villages on three approaches to target the poor proxy means tests pmt where assets are used to predict consumption community targeting where villagers rank everyone from richest to poorest and a hybrid defining poverty based on ppp 2 per capita consumption community targeting and the hybrid perform somewhat worse in identifying the poor than pmt though not by enough to significantly affect poverty outcomes for a typical program elite capture does not explain these results instead communities appear to apply a different concept of poverty

technological learning and renewable energy costs implications for us renewable energy policy abstract this paper analyzes the relationship between current renewable energy technology costs and cumulative production research development and demonstration expenditures and other institutional influences combining the theoretical framework of learning by doing and developments in learning by searching with the fields of organizational learning and institutional economics offers a complete methodological framework to examine the underlying capital cost trajectory when developing electricity cost estimates used in energy policy planning models sensitivities of the learning rates for global wind and solar photovoltaic technologies to changes in the model parameters are tested the implications of the results indicate that institutional policy instruments play an important role for these technologies to achieve cost reductions and further market adoption

the formation of risk sharing networks this paper examines the formation of risk sharing networks in the rural philippines we find that geographic proximity possibly correlated with kinship is a major determinant of mutual insurance links among villagers age and wealth differences also play an important role in contrast income correlation and differences in occupation are not determinants of network links reported network links have a strong effect on subsequent gifts and loans gifts between network partners are found to respond to shocks and to differences in health status from this we conclude that intra village mutual insurance links are largely determined by social and geographical proximity and are only weakly the result of purposeful diversification of income risk the paper also makes a methodological contribution to the estimation of dyadic models

new insights into smile mispricing and value at risk the hyperbolic model the authors investigate a new basic model for asset pricing the hyperbolic model which allows an almost perfect statistical fit of stock return data after a detailed introduction into the theory they use secondary market data to compare the hyperbolic model to the classical black scholes model the authors study implicit volatilities the smile effect and pricing performance exploiting the full power of the hyperbolic model they construct an option value process from a statistical point of view by estimating the implicit risk neutral density function from option data finally the authors present some new value at risk calculations leading to new perspectives to cope with model risk copyright 1998 by university of chicago press

a real option model for renewable energy policy evaluation with application to solar pv power generation in china abstract this study proposes a policy evaluation model from the perspective of government and investors the proposed model which integrates american option method and two factor learning curve method can be used to evaluate the unit decision value and save path rate for renewable energy development and examine the existence of balance point of interest several uncertain factors including non renewable energy cost carbon price renewable energy cost and price subsidy are all considered in this model the model has been applied to evaluate the solar photovoltaic pv power generation in china our empirical results show that real option analysis roa is more effective than net present value analysis npv when handling uncertainty under current level of subsidy the government would suffer loss and the investors could benefit so that it is difficult to achieve the balance of interest during the planning period with the reduction of subsidy rate they can achieve the balance of interest

politician family networks and electoral outcomes evidence from the philippines we demonstrate the electoral importance of politician family networks and provide evidence of the mechanisms behind the relationship we use a 20 million person dataset allowing us to reconstruct intermarriage networks for over 15 000 villages in 709 municipalities in the philippines we show that politicians are disproportionately drawn from more central families and that controlling for candidate fixed e ects candidates receive a higher vote share in villages where their families are more central we present evidence that centrality confers organizational and logistical advantages that facilitate clientelistic transactions such as vote buying and do not operate through popularity name recognition or through the choice of policies more aligned with their constituents preferences

peer effects and social networks in education this paper studies whether structural properties of friendship networks affect individual outcomes in education we first develop a model that shows that at the nash equilibrium the outcome of each individual embedded in a network is proportional to her katz bonacich centrality measure this measure takes into account both direct and indirect friends of each individual but puts less weight to her distant friends we then bring the model to the data by using a very detailed dataset of adolescent friendship networks we show that after controlling for observable individual characteristics and unobservable network specific factors the individual s position in a network as measured by her katz bonacich centrality is a key determinant of her level of activity a standard deviation increase in the katz bonacich centrality increases the pupil school performance by more than 7 percent of one standard deviation

local inequality and project choice theory and evidence from ecuador this paper provides evidence consistent with elite capture of social fund investment projects in ecuador exploiting a unique combination of data sets on village level income distributions social fund project administration and province level electoral results we test a simple model of project choice when local political power is unequally distributed in accordance with the predictions of the model poorer villages are more likely to receive projects that provide excludable private goods to the poor such as latrines controlling for poverty more unequal communities are less likely to receive such projects consistent with the hypothesis of elite capture these results are sensitive to the specific measures of inequality and elite power used in the empirical analysis and are strongest for expenditure shares at the top of the distribution

quantitative study on long term global solar photovoltaic market abstract this paper analyzes the relationship between the declines in solar photovoltaic pv module costs and cumulative production silicon prices supply demand imbalance and the presence of lower cost chinese products in global pv market using learning curve model state of market development and its connection with learning is also examined results indicate that learning effect is best measured when supplementing output with silicon prices in the analysis learning rate lr diminishes over the time periods examined thereby suggesting the declining of progress as market reaches maturity the outcomes from the learning curve analysis are subsequently applied to project future uptake of pv worldwide module and electricity costs till 2035 demand for pv is anticipated to remain robust with cumulative installed capacity worldwide projected to reach 659 gw by 2035 at the same time module cost is estimated to decline from 3 8 w in 2006 to 1 78 w in 2035 a reduction of over 50 relative to 2006 level unit cost of electricity from pv is predicted to be in the range of 0 13 kwh to 0 17 kwh by 2035 for the three scenarios analyzed

how does development assistance affect collective action capacity results from a field experiment in post conflict liberia social cooperation is critical to a wide variety of political and economic outcomes for this reason international donors have embraced interventions designed to strengthen the ability of communities to solve collective action problems especially in post conflict settings we exploit the random assignment of a development program in liberia to assess the effects of such interventions using a matching funds experiment we find evidence that these interventions can alter cooperation capacity however we observe effects only in communities in which by design both men and women faced the collective action challenge focusing on mechanisms we find evidence that program effects worked through improvements in mobilization capacity that may have enhanced communities ability to coordinate to solve mixed gender problems these gains did not operate in areas where only women took part in the matching funds experiment possibly because they could rely on traditional institutions unaffected by the external intervention the combined evidence suggests that the impact of donor interventions designed to enhance cooperation can depend critically on the kinds of social dilemmas that communities face and the flexibility they have in determining who should solve them

social connections and group banking lending to the poor is expensive due to high screening monitoring and enforcement costs group lending advocates believe lenders overcome this by harnessing social connections using data from finca peru i exploit a quasi random group formation process to find evidence of peers successfully monitoring and enforcing joint liability loans individuals with stronger social connections to their fellow group members i e either living closer or being of a similar culture have higher repayment and higher savings furthermore i observe direct evidence that relationships deteriorate after default and that through successful monitoring individuals know who to punish and who not to punish after default

technological learning in energy environment economy modelling a survey abstract this paper aims at providing an overview and a critical analysis of the technological learning concept and its incorporation in energy environment economy models a special emphasis is put on surveying and discussing through the so called learning curve both studies estimating learning rates in the energy field and studies incorporating endogenous technological learning in bottom up and top down models the survey of learning rate estimations gives special attention to interpreting and explaining the sources of variability of estimated rates which is shown to be mainly inherent in r d expenditures the problem of omitted variable bias the endogeneity relationship and the role of spillovers large scale models survey show that despite some methodological and computational complexity related to the non linearity and the non convexity associated with the learning curve incorporation results of the numerous modelling experiments give several new insights with regard to the analysis of the prospects of specific technological options and their cost decrease potential bottom up models and with regard to the analysis of strategic considerations especially inherent in the innovation and energy diffusion process in particular the energy sector s endogenous responses to environment policy instruments top down models

cost and co2 reductions of solar photovoltaic power generation in china perspectives for 2020 abstract to improve the understanding of the cost and benefit of photovoltaic pv power generation in china we analyze the per kwh cost fossil energy replacement and level of co2 mitigation as well as the cost per unit of reduced co2 of pv power generation in 2020 at the province level three potential pv systems are examined large scale pv lspv building integrated pv bipv and distributed pv systems used in remote rural areas which have very low capacities the results show that in 2020 pv power generation could save 17 4 mtce fossil energy and 46 5 tg co2 compared with 600 mwe coal fired supercritical units also in 2020 the costs of solar electricity could be reduced by approximately 60 as compared to 2010 but would still be 11 74 higher than the current grid prices the pv electricity costs vary significantly among provinces in the economically developed eastern provinces the pv electricity mainly bipv is 0 67 0 86 rmb kwh this rate is close to grid parity owing to high grid prices but the co2 mitigation cost is high 456 693 rmb mg co2 the pv electricity mainly lspv in solar resource rich western provinces has lower cost 0 45 0 75 rmb kwh and lower co2 mitigation cost 172 419 rmb mg co2 but is farther from grid parity due to the low local grid price from a cost effective perspective lspv in the west provinces should be the first priority in pv deployment strategies and should receive strong financial support from the government this study provides a quantitative province specific analysis of pv power generation which can be used to support various pv subsidy policies

a global and local endogenous experience curve model for projecting future uptake and cost of electricity generation technologies abstract a global and local learning model gallm has been developed to project the cost and global uptake of different electricity generation technologies to the year 2050 this model features three regions endogenous technological learning within and across those regions various government policies to facilitate technological learning and a penalty constraint which is used to mimic the effect market forces play on the capital cost of electricity generation technologies this constraint has been added as market forces have been a strong factor in technology pricing in recent years global regional and component experience curves have been developed for some technologies the model with the inclusion of these features projects a diverse range of technologies contributing to global electricity generation under a carbon price scenario the penalty constraint leads to gradual and continual installations of technologies and because the constraint provides a disincentive to install too much of a technology it reduces the impact of uncertainty in the learning rate alternative forms of the penalty constraint were tested for their suitability it was found that with a zero and lower cost version of the constraint photovoltaics are installed in a boom and bust cycle which is not supported by past experience when the constraint is set at a high level there are fewer installations

a review of learning rates for electricity supply technologies a variety of mathematical models have been proposed to characterize and quantify the dependency of electricity supply technology costs on various drivers of technological change the most prevalent model form called a learning curve or experience curve is a log linear equation relating the unit cost of a technology to its cumulative installed capacity or electricity generated this one factor model is also the most common method used to represent endogenous technical change in large scale energy economic models that inform energy planning and policy analysis a characteristic parameter is the learning rate defined as the fractional reduction in cost for each doubling of cumulative production or capacity in this paper a literature review of the learning rates reported for 11 power generation technologies employing an array of fossil fuels nuclear and renewable energy sources is presented the review also includes multi factor models proposed for some energy technologies especially two factor models relating cost to cumulative expenditures for research and development r d as well as the cumulative installed capacity or electricity production of a technology for all technologies studied we found substantial variability as much as an order of magnitude in reported learning rates across different studies such variability is not readily explained by systematic differences in the time intervals geographic regions choice of independent variable or other parameters of each study this uncertainty in learning rates together with other limitations of current learning curve formulations suggests the need for much more careful and systematic examination of the influence of how different factors and assumptions affect policy relevant outcomes related to the future choice and cost of electricity supply and other energy technologies

reshaping institutions evidence on aid impacts using a pre analysis plan this brief summarizes the results of a gender impact evaluation study entitled reshaping institutions evidence on aid impacts using a pre analysis plan conducted between 2005 and 2009 in sierra leone the study observed the impact of pre analysis plan pap on local institutions by imposing participation requirements for marginalized groups including women and test for learning by doing effects in sierra leone on the individual and village level requiring women and young adults to take on leadership positions participate in project meetings and sign off on project finances does not have any persistent effect on their participation in local decision making or attitudes regarding leadership ability the project successfully established village organizations and tools to manage the project the distributions of the project s benefits were equitable and leakage was minimal there was a significant positive impact on the stock and quality of local public infrastructure however there are no detectible changes in the ability to raise funds for local public goods decision making process or social norms and attitudes funding for the study derived from the gobifo project the institutional reform and capacity building project ircbp the world bank development impact evaluation dime the horace w goldsmith foundation the international growth center 3ie and the national bureau of economic research nber african successes project

do household definitions matter in survey design results from a randomized survey experiment in mali abstract household definitions used in multi topic household surveys vary between surveys but have potentially significant implications for household composition production and poverty statistics standard definitions of the household usually include some intersection of keywords relating to residency requirements common food consumption and intermingling of income or production decisions despite best practices intending to standardize the definition of the household it is unclear which types of definitions or which intersections of keywords in a definition result in different household compositions this paper conducts a randomized survey experiment of four different household definitions in mali to examine the implications for household level statistics this approach permits analysis of the trade offs between alternative definition types we find that additional keywords in definitions increase rather than decrease household size and significantly alters household composition definitions emphasizing common consumption or joint production increase estimates of the levels of household assets and consumption statistics but not on per adult equivalency asset and consumption statistics relative to open ended definitions of the household in contrast definition type did not affect production statistics in levels though we observe significant differences in per adult equivalency terms our findings suggest that variations in household definition have implications for measuring household welfare and production

can good projects succeed in bad communities abstract the lack of social capital is frequently given as an explanation for why communities perform poorly yet to what extent can project design compensate for these community specific constraints i address this question by examining determinants of collective success in a costly problem for developing economies the upkeep of local public goods it is often difficult to obtain reliable outcome measures for comparable collective tasks across well defined communities in order to address this i conducted detailed surveys of community maintained infrastructure projects in northern pakistan the findings show that while community specific constraints do matter their impact can be mitigated by better project design inequality social fragmentation and lack of leadership in the community do have adverse consequences but these can be overcome by changes in project complexity community participation and return distribution moreover the evidence suggests that better design matters even more for communities with poorer attributes the use of community fixed effects and instrumental variables offers a significant improvement in empirical identification over previous studies these results provide evidence that appropriate design can enable projects to succeed even in bad communities

the impact of r d on innovation for wind energy in denmark germany and the united kingdom this paper examines the impact of public research and development r d support on cost reducing innovation for wind turbine farms in denmark germany and the united kingdom uk first we survey the literature in this field the literature indicates that in denmark r d policy has been more successful than in germany or the uk in promoting innovation of wind turbines furthermore such studies point out that subsidy induced capacity expansions were more effective in the uk and denmark in promoting cost reducing innovation than in germany the second part of the paper describes the quantitative analysis of the impact of r d and capacity expansion on innovation this is calculated using the two factor learning curve 2flc model in which investment cost reductions are explained by cumulative capacity and the r d based knowledge stock time series data were collected for the three countries and organized as a panel data set the parameters of the 2flc model were estimated focusing on the homogeneity and heterogeneity of the parameters across countries we arrived at robust estimations of a learning by doing rate of 5 4 and a learning by searching rate of 12 6 the analysis underlines the homogeneity of the learning parameters enhancing the validity of the 2flc formulation

aid under fire development projects and civil conflict we estimate the causal effect of a large development program on conflict in the philippines through a regression discontinuity design that exploits an arbitrary poverty threshold used to assign eligibility for the program we find that barely eligible municipalities experienced a large increase in conflict casualties compared to barely ineligible ones this increase is mostly due to insurgent initiated incidents in the early stages of program preparation our results are consistent with the hypothesis that insurgents try to sabotage the program because its success would weaken their support in the population

social capital and social quilts network patterns of favor exchange we examine the informal exchange of favors in societies such that any two individuals interact too infrequently to sustain exchange but such that the social pressure of the possible loss of multiple relationships can sustain exchange patterns of exchange that are locally enforceable and renegotiation proof necessitate that all links are supported any two individuals exchanging favors have a common friend in symmetric settings such robust networks are social quilts tree like unions of completely connected subnetworks examining favor exchange networks in 75 villages in rural india we find high levels of support and identify characteristics that correlate with support

network structure and the aggregation of information theory and evidence from indonesia abstract we use unique data from over 600 indonesian communities on what individuals know about the poverty status of others to study how network structure influences information aggregation we develop a model of semi bayesian learning on networks which we structurally estimate using within village data the model generates qualitative predictions about how cross village patterns of learning relate to network structure which we show are borne out in the data we apply our findings to a community based targeting program where citizens chose households to receive aid and show that the networks that the model predicts to be more diffusive differentially benefit from community targeting jel d14 d83 d85 i32 o12 z13

networks markets and inequality julien gagnon thanks the gates cambridge trust for financial support sanjeev goyal is grateful to the keynes fellowship and the cambridge inet institute for financial support

trust and social collateral this paper builds a theory of trust based on informal contract enforcement in social networks in our model network connections between individuals can be used as social collateral to secure informal borrowing we define network based trust as the largest amount one agent can borrow from another agent and derive a reduced form expression for this quantity which we then use in three applications 1 we predict that dense networks generate bonding social capital that allows transacting valuable assets whereas loose networks create bridging social capital that improves access to cheap favors such as information 2 for job recommendation networks we show that strong ties between employers and trusted recommenders reduce asymmetric information about the quality of job candidates 3 using data from peru we show empirically that network based trust predicts informal borrowing and we structurally estimate and test our model

inequality reciprocity and credit in social networks while informal insurance and social networks are important in all societies networks are critical in rural areas of developing countries townsend 1994 was one of the first to document the importance of risk sharing within villages more recently theorists have begun to model sharing as taking place within a network rather than within the village as a whole bramoulle and kranton 2007 bloch genicot and ray 2008 ambrus mobius and szeidl 2010 empirical studies have also shown the importance of risk sharing within social networks rosenzweig 1988 udry 1994 de weerdt and dercon 2006 given this local nature of risksharing within networks it is important to analyze who forms links with whom and the types of relationships formed the effects of development policies will depend on the operation of social networks and the features that cause individuals to form links research on the determinants of risk sharing links has found contradictory results experimental studies such as attanasio et al 2009 find that risk sharing groups are assortative on consumption survey based evidence such as de weerdt 2004 and fafchamps and gubert 2007 find laura schechter is an assistant professor of economics at michigan state university alex yuskavage is a financial economist in the office of tax analysis at the u s treasury schechter thanks the wisconsin alumni research foundation the russell sage foundation and the delta foundation for funding we are grateful to idelin molinas and instituto desarrollo for their support in paraguay jennifer alix garcia joachim de weerdt garance genicot paul niehaus mark rosenzweig and guanming shi gave helpful comments

power to the people evidence from a randomized field experiment on community based monitoring in uganda this brief summarizes the results of a gender impact evaluation study entitled power to the people evidence from a randomized field experiment on community based monitoring in uganda intervention started in 2004 and consisted of a training and a six month follow up in uganda the study observed that localized nongovernmental organizations encouraged communities to be more involved with the state of health service provision and strengthened their capacity to hold their local health providers to account for performance the community based monitoring project increased the quality and quantity of primary health care provision the program led to a significant increase in the weight of infants by 14 z scores and a significant decrease in child mortality by 33 utilization of outpatient services was significantly higher 20 percent in the treatment group and the overall effect across utilization measures is large and significant funding for the study derived from bank netherlands partnership program world bank research committee world bank africa region division swedish international development agency department for research cooperation

institutions and behavior experimental evidence on the effects of democracy a novel experiment is used to show that the effect of a policy on the level of cooperation is greater when it is chosen democratically by the subjects than when it is exogenously imposed in contrast to the previous literature our experimental design allows us to control for selection effects e g those who choose the policy may be affected differently by it our finding implies that democratic institutions may affect behavior directly in addition to having effects through the choice of policies our findings have implications for the generalizability of the results of randomized policy interventions

backtesting trading risk of commercial banks using expected shortfall this paper uses saddlepoint technique to backtest the trading risk of commercial banks using expected shortfall it is found that four out of six us commercial banks have excessive trading risks monte carlo simulation studies show that the proposed backtest is very accurate and powerful even for small test samples more importantly risk managers can carry out the proposed backtest based on any number of exceptions so that incorrect risk models can be promptly detected before any further huge losses are realized

us food aid and civil conflict we study the effect of us food aid on conflict in recipient countries our analysis exploits time variation in food aid shipments due to changes in us wheat production and cross sectional variation in a country s tendency to receive any us food aid according to our estimates an increase in us food aid increases the incidence and duration of civil conflicts but has no robust effect on interstate conflicts or the onset of civil conflicts we also provide suggestive evidence that the effects are most pronounced in countries with a recent history of civil conflict jel d74 f35 o17 o19 q11 q18 we are unable to determine whether our aid helps or hinders one or more parties to the conflict it is clear that the losses particularly looted assets constitutes a serious barrier to the efficient and effective provision of assistance and can contribute to the war economy this raises a serious challenge for the humanitarian community can humanitarians be accused of fueling or prolonging the conflict in these two countries medecins sans frontieres amsterdam 1

consumption risk sharing in social networks we develop a model of informal risk sharing in social networks where relationships between individuals can be used as social collateral to enforce insurance payments we characterize incentive compatible risk sharing arrangements and obtain two results 1 the degree of informal insurance is governed by the expansiveness of the network measured by the number of connections that groups of agents have with the rest of the community relative to group size twodimensional networks where people have connections in multiple directions are su ciently expansive to allow very good risk sharing we show that social networks in peruvian villages satisfy this dimensionality property thus our model can explain townsend s 1994 puzzling observation that village communities often exhibit close to full insurance 2 in second best arrangements agents organize in endogenous risk sharing islands in the network where shocks are shared fully within but imperfectly across islands as a result network based risk sharing is local socially closer agents insure each other more

can development aid contribute to social cohesion after civil war evidence from a field experiment in post conflict liberia civil war is very common in the develop ing world with harmful welfare effects when it occurs many fear that the devastation wrought by violent conflict destroys social capital impedes economic development and leads to the recur rence of violence paul collier et al 2003 in response donors are injecting large amounts of aid into post conflict countries a significant share of this assistance is spent on community driven reconstruction cdr programs which support the establishment of new local institu tions in order to promote social reconciliation whether this assistance has this effect is how ever largely unknown can brief foreign funded efforts to build local institutions in fact have posi tive effects on local patterns of cooperation we address this question using a randomized field experiment to evaluate the impact of a cdr project in northern liberia the project was funded by the united kingdom s department for international development dfid and imple mented by the international rescue committee irc the project attempted to build demo cratic community level institutions for making and implementing decisions about local public goods this model of support for participatory processes to enhance local public goods provi

economic analysis of the contribution of photovoltaics to the decarbonization of the power sector abstract an analytical method has been developed for the calculation of the future 2013 2050 reduction of co2 emissions by the deployment of photovoltaic pv systems according to three scenarios from the international energy agency 2ds roadmap and new policies next we have also evaluated the financial extra costs incurred in the implementation of the pv systems which would replace the current traditional power generation systems taking as reference four geographical areas european union united states china and the world s average the established method also allows the comparison of the influence on the extra costs of the actual electricity mix as well as the current electricity prices corresponding to the above regional areas in these calculations we have taken into account several frequently ignored factors like solar cell degradation emissions attributed to the pv systems life cycle and the repowering due to the substitution of the systems after their life time is reached finally the results of this work can be of interest in energy planning policies related to the contribution of pv technologies for the decarbonization of the power generation system

unraveling the photovoltaic technology learning curve by incorporation of input price changes and scale effects in a large number of energy models the use of learning curves for estimating technological improvements has become popular this is based on the assumption that technological development can be monitored by following cost development as a function of market size however recent data show that in some stages of photovoltaic technology pv production the market price of pv modules stabilizes even though the cumulative capacity increases this implies that no technological improvement takes place in these periods the cost predicted by the learning curve in the pv study is lower than the market one we propose that this bias results from ignoring the effects of input prices and scale effects and that incorporating the input prices and scale effects into the learning curve theory is an important issue in making cost predictions more reliable in this paper a methodology is described to incorporate the scale and input prices effect as the additional variables into the one factor learning curve which leads to the definition of the multi factor learning curve this multi factor learning curve is not only derived from economic theories but also supported by an empirical study the results clearly show that input prices and scale effects are to be included and that although market prices are stabilizing learning is still taking place

risk models at risk the experience from the global financial crisis has raised serious concerns about the accuracy of standard risk measures as tools for the quantification of extreme downward risks a key reason for this is that risk measures are subject to a model risk due e g to specification and estimation uncertainty while regulators have proposed that financial institutions assess the model risk there is no accepted approach for computing such a risk we propose a remedy for this by a general framework for the computation of risk measures robust to model risk by empirically adjusting the imperfect risk forecasts by outcomes from backtesting frameworks considering the desirable quality of var models such as the frequency independence and magnitude of violations we also provide a fair comparison between the main risk models using the same metric that corresponds to model risk required corrections

dynamics of energy technologies and global change technological choices largely determine the long term characteristics of industrial society including impacts on the natural environment however the treatment of technology in existing models that are used to project economic and environmental futures remains highly stylized based on work over two decades at iiasa we present a useful typology for technology analysis and discuss methods that can be used to analyze the impact of technological changes on the global environment especially global warming our focus is energy technologies the main source of many atmospheric environmental problems we show that much improved treatment of technology is possible with a combination of historical analysis and new modeling techniques in the historical record we identify characteristic l such network e ects yield high barriers to entry even for superior competitors these simple observations allow three improvements to modeling of technological change and its consequences for global environmental change one is that the replacement of long lived infrastructures over time has also replaced the fuels that power the economy to yield progressively more energy per unit of carbon pollution from coal to oil to gas such replacement has d they also include endogenous generation of s we show that doing so can yield projections with lessened environmental impacts without necessarily incurring negative e ect on the economy arriving on that path by the year 2100 depends on intervening actions such as incentives to promote greater diversity in technology and lower barriers to entry for new infrastructures that could accelerate historical trends of decarbonization 1999 elsevier science ltd all rights reserved