competition between multiple asymmetric networks theory and applications this paper presents a tractable model of network competition with many firms elastic subscriber demand off net price discrimination call externalities and cost and market share asymmetries we characterize stability in expectations and equilibrium under firm and market level network effects the model is applied to simulate the effects of termination rates market maturity and retail pricing strategies we show that predictions based on duopoly models can be misleading in particular concerning the effects of termination rates

seasonal poverty in madagascar magnitude and solutions abstract seasonal reductions in food consumption pull about one million malagasy below the poverty line during the lean season there they join the nine million more who remain chronically undernourished throughout the year because the seasonality of food shortages coincides with the increased prevalence of diarrhea and other diseases during the rainy season the resulting lean season exacts a heavy toll in the form of increased rates of malnutrition and child mortality combining the results of recent field studies with a seasonal multi market model this paper measures the probable impacts of three common interventions aimed at combatting seasonal food insecurity we find the most promising interventions to be those that increase agricultural productivity of the secondary food crops such as cassava other roots and tubers and maize

promoting network competition by regulating termination charges abstract this paper contributes to the policy debate about the optimal termination charge when penetration rates are explicitly taken into account although lowering termination charges towards cost leads to more efficient usage its impact on consumer surplus is ambiguous since it induces an increase in fixed subscription fee through the so called waterbed effect we show that a reduction in termination charge below cost has two opposing effects on consumer surplus it softens competition but also helps to internalize network externalities hence it can decrease or increase penetration depending on whether or not the first effect dominates the second we show that the first effect dominates the second when networks are weak substitutes or the penetration rate is high

bill and keep vs cost based access pricing revisited abstract we study network competition with two part tariffs and termination based price discrimination in the presence of call externalities we show that both the collusive and the welfare maximizing access charges fall below marginal cost moreover bill and keep arrangements are welfare improving compared with cost based access pricing

national accounting and the valuation of ecosystem assets and their services there has long been interest in integrating the value of environmental stocks and flows into standard measures of economic activity and wealth in particular through the development of adjusted measures of gdp and extended measures of national wealth this paper examines how the valuation of ecosystem services and ecosystem assets can be undertaken in an integrated national accounting setting we clarify the relevant valuation principles most significantly the need to apply the concept of exchange values and explain why the integration of ecosystem services necessitates an extension of the standard production boundary used in economic measurement the main implications of an accounting approach are discussed including the need to distinguish benefits from services the need for valuation methods that exclude consumer surplus and the importance of aligning measures of income and degradation remaining challenges include the treatment of low or negative rents accounting for ecosystem disservices and the derivation of values for ecosystem assets meeting these challenges and advancing work in this area should be the joint focus of economists ecologists and accountants

sustaining growth in agriculture a quantitative review of agricultural research investments abstract growth in agriculture depends on many things but one of the most important is investment in agricultural research decision making in the agricultural research policy area can only be aided by access to better information this article overviews a recent endeavor to move policy dialogue beyond merely qualitative impressions towards a process that is underpinned with new and cogent data the data used have been assembled at isnar in a manner designed to make comparisons both over time and between countries more valid than has been the case in the past the comparisons thus possible reveal considerable diversity both between countries and between broad regional aggregations also illuminated here are issues related to the commodity orientation capital and labor intensity and size and scope of particular national programs

using bill and keep interconnect arrangements to soften network competition abstract this paper demonstrates that low below marginal cost interconnect or access charges can be used to sustain high subscription prices under network competition with two part tariffs and price discrimination this result stands in contrast to other results in the literature suggesting that high interconnect charges can play a collusive role

measuring sustainability in the un system of environmental economic accounting the adoption of the system of environmental economic accounting 2012 central framework as a un statistical standard is a landmark in environmental accounting the seea has the same authority and weight as the system of national accounts in the pantheon of official statistics the seea defines the unit value of depletion of an exhaustible resource to equal the average unit value of the asset the total asset value divided by the physical stock of resource by applying this definition to a non optimal dasgupta heal solow model of an extractive economy we show that depletion adjusted net saving as defined in the seea supports a generalized version of the hartwick rule this measure of saving can guide policies for sustainable development in extractive economies in particular fiscal policies concerning consumption and investment expenditures funded by resource rents the conditions required to support this finding are i that extraction declines over time at a constant rate and ii that the marginal cost of resource extraction is constant a less general result holds in the case of increasing marginal extraction costs

price regulation of access to telecommunications networks abstract without access of networks to each other competition in the telecommunications sector would hardly have spread so quickly such mutual access is necessary for carriers to provide ubiquitous service and enable endusers to call and be called by anybody without subscribing to a system wide monopolist one way access concerns bottleneck inputs provided by an incumbent network to entrants while two way access concerns the interconnection between networks whereas one way access regulation is exclusively driven by containment of market power two way access is additionally affected by collusion possibilities among the numerous pricing rules discussed none clearly dominates this article provides a roadmap vis a vis the competing policy objectives for access price regulation

underinvestment in a profitable technology the case of seasonal migration in bangladesh hunger during pre harvest lean seasons is widespread in the agrarian areas of asia and sub saharan africa we randomly assign an 8 50 incentive to households in rural bangladesh to temporarily out migrate during the lean season the incentive induces 22 of households to send a seasonal migrant their consumption at the origin increases significantly and treated households are 8 10 percentage points more likely to re migrate 1 and 3 years after the incentive is removed these facts can be explained qualitatively by a model in which migration is risky mitigating risk requires individual specific learning and some migrants are sufficiently close to subsistence that failed migration is very costly we document evidence consistent with this model using heterogeneity analysis and additional experimental variation but calibrations with forward looking households that can save up to migrate suggest that it is difficult for the model to quantitatively match the data we conclude with extensions to the model that could provide a better quantitative accounting of the behavior

available capital utilized capital and shadow prices in inclusive wealth accounting abstract previously accounting for comprehensive or inclusive wealth has focused on the supply side of capital assets however human well being created by capital assets inherently depends on the demand side as well in particular if capital is not utilized at its full capacity then realized or actual human well being may be less affected by available capital than by effective or utilized capital in principle this notion is embodied in a shadow price which is defined as the marginal contribution of capital assets to social well being the shadow price becomes higher if the underlying resource allocation mechanism improves in practice one can account for such underutilization by adjusting shadow prices to reflect only the utilized quantity of the capital in question furthermore capital utilization has different nuanced implications for produced human and natural capital and its implications even vary across some classes of natural capital within this line of theoretical thought we provide empirical estimates of the changes in inclusive wealth and sustainability of selected developing countries in recent years by comparing available and utilized capital assets we find that sustainability assessments may be revised based on utilized capital due to among others human capital underemployment and non renewable natural capital accessibility

calling circles network competition with non uniform calling patterns we introduce a flexible model of telecommunications network competition with nonuniform calling patterns accounting for the fact that customers tend to make most calls to a small set of similar people equilibrium call prices are distorted away from marginal cost and competitive intensity is affected by the concentration of calling patterns contrary to previous predictions jointly profit maximizing access charges are set above termination cost in order to dampen competition if calling patterns are sufficiently concentrated we discuss implications for regulating access charges as well as on and off net price discrimination

foreclosing competition through high access charges and price discrimination this article analyzes competition between two asymmetric networks an incumbent and a new entrant networks compete in non linear tariffs and may charge different prices for on net and off net calls when access charges are high this allows the incumbent to foreclose the market in a profitable way if switching costs are sufficiently large in the absence of termination based price discrimination however such foreclosure strategies are not profitable

food marketing liberalization and trader entry evidence from madagascar abstract food marketing liberalization was expected to induce massive trader entry and competitive markets in africa despite evidence of trader entry enterprise expansion remains difficult and many claim market power persists though perhaps in different hands this paper confronts this puzzle of substantial market entry that might not foster competition data from madagascar reveal distinct groups within rural food marketing channels separated by intraindustry mobility barriers that limit entry to a few niches moreover individuals place within the rural marketing network is defined largely by a priori social identity so the experience of food marketing liberalization varies across socially distinct subpopulations

information exchange and competition in communications networks we develop a model of information exchange between calling parties we characterize the equilibrium when two interconnected networks compete by charging both for outgoing and incoming calls we show that networks have reduced incentives to use off net price discrimination to induce a connectivity breakdown when calls originated and received are complements in the information exchange this breakdown disappears if operators are allowed to negotiate reciprocal access charges we also study the relationship between sending and receiving retail charges as a function of the level of access charges we identify circumstances where private negotiations over access charges induce first best retail prices i introduction people use electronic communications in order to exchange information this exchange may take very different forms take as an example a situation with two individuals a and b a and b are academics trying to work on a joint paper but live in different places thus they rely on telephone conversations and e mail exchanges to conduct their work one day a and b are struggling to solve an equation a finds the solution and calls b b is obviously happy but then does not need to call a back since the problem has been solved another day a has an embryo of an idea and calls b b needs some time to ponder over this rudimental idea and then calls a back to tell him what she thinks about it in this second case b is still happy to have received a call from a since it may lead to an improvement of their paper but now the original call has initiated a chain reaction that has led b to return the call

food price seasonality in africa measurement and extent everyone knows about seasonality but what exactly do we know this study systematically measures seasonal price gaps at 193 markets for 13 food commodities in seven african countries it shows that the commonly used dummy variable or moving average deviation methods to estimate the seasonal gap can yield substantial upward bias this can be partially circumvented using trigonometric and sawtooth models which are more parsimonious among staple crops seasonality is highest for maize 33 percent on average and lowest for rice 16 percent this is two and a half to three times larger than in the international reference markets seasonality varies substantially across market places but maize is the only crop in which there are important systematic country effects malawi where maize is the main staple emerges as exhibiting the most acute seasonal differences reaching the sustainable development goal of zero hunger requires renewed policy attention to seasonality in food prices and consumption

shifting sands the changing case for monetizing project food aid in bangladesh abstract monetization involves local sale of food aid commodities and using the cash to finance other programs to explore the likely consequences of monetization this paper combines a stockpile of recent microeconomic evidence from food and cash for work projects in bangladesh together with a multimarket simulation model results suggest that a switch from food for work s ffw in kind deliveries of wheat to an identical wheat financed cash for work cfw program would unambiguously improve welfare of the poor

urban bias in price risk the geography of food price distributions in low income economies the geography of agricultural marketing has important implications for the stochastic distribution of agricultural commodity prices this article proposes that objective food price risk differs between rural and urban areas of infrastructure poor economies characterised by spatially concentrated patterns of foodgrains storage this difference implies an urban bias having adverse welfare effects for peasants who seasonally switch between net food seller and net food buyer positions empirical analysis of rice price data from madagascar suggests that price variability and skewness indeed differ between rural and urban areas in ways that adversely influence the relative welfare of rural peasants

network interconnection in telecommunications this paper discusses industries such as telecommunications where firms each have their own customers and must interconnect with other firms to provide a comprehensive service two scenarios are considered i the case of a symmetric unregulated industry and ii the case of an industry with a dominant regulated incumbent in the first provided there is sufficient product differentiation it is shown that firms agree to set interconnection charges above associated costs in order to obtain the joint profit maximising outcome in the second a formula for the welfare maximizing interconnection charge is derived relations with the efficient component pricing rule are discussed

sources of food price volatility and child malnutrition in niger and malawi in recent times considerable attention has been paid to the nutritional impact of the sharp hikes in the international food prices which took place in 2007 8 and 2010 11 while understandable this growing focus has perhaps obscured the impact of other variables affecting malnutrition in sub saharan africa i e the long term impact of agricultural policies on food supply and prices large and persistent seasonal variations in food prices and the impact of famines which still affect parts of the continent this paper focuses on the relative impact of these factors on child malnutrition measured by the number of child admissions to feeding centres in malawi and niger two countries which closely represent the situation of other small landlocked subsistence agricultural economies facing severe food security problems our analysis shows that in these countries the drivers of changes in domestic staple prices and child malnutrition are related not only or not primarily to variations of international food prices but also to the impact of agricultural policies on food production and prices in a persistent food price seasonality and in recurrent and poorly managed famines these factors can exert a strong upward pressure on food prices and child malnutrition even during years of falling international prices

seasonality of income and poverty in bangladesh abstract seasonal food deprivation in bangladesh locally known as monga sometimes rises to the level of famine during the pre harvest period of aman rice an analysis of household income and expenditure survey data shows that income and consumption are lower during monga than in other seasons and that seasonal income greatly influences seasonal consumption econometric estimates reject the hypothesis of perfect consumption smoothing in the northwestern region of greater rangpur rural households suffer disproportionately from monga seasonal differences in poverty across regions are due mainly to differences in household specific seasonality of income and consumption income diversification explains the lower incidence of income seasonality observed in non rangpur regions to contain seasonal hunger in greater rangpur public policies should promote rural income diversification together with seasonal migration a flexible microfinance scheme that provides both production and consumption loans on flexible repayment terms could help diversify income and reduce seasonality of income and poverty

network competition i overview and nondiscriminatory pricing we develop a model of unregulated competition between interconnected networks and analyze the mature and transition phases of the industry in this deregulated environ ment networks pay negotiated or regulated access charges to each other and com pete in prices for customers we show that a competitive equilibrium may fail to exist for large access charges or for large network substitutability and that freely negotiated access charges may prevent effective competition in the mature phase of the industry and erect barriers to entry in the transition toward competition last we examine the meaning and impact of policies such as the efficient component pricing rule

the liberalization of rice marketing in madagascar abstract madagascar s experience with rice marketing liberalization between 1985 and 1988 illustrates the many obstacles in the way of effective deregulation of agricultural markets the resistance of ambiguous regulation continuing limits on free entry attempts at cartelization and tenacious resistance of existing stakeholders and institutions at the same time the experience shows the ability of higher prices and freer markets to overcome much of this resistance and to stimulate production even in the presence of so called structural constraints such as poor roads weak extension services inadequate credit systems and input supply arrangements