the demand for food products an analysis of interpurchase times and purchased quantities in this paper we study household purchase behaviour of storable food products an inventory model is developed in which the household chooses an optimal stock level of the product storage of the product is costly there is a fixed cost per purchase occasion and the market price is sometimes discounted because of price promotions we show that the optimal purchase policy is an s s policy the model is used to derive predictions on the correlations between interpurchase times and purchased quantities on the one hand and prices on the other these predictions are empirically verified using consumer panel data

nonconvexities in the production of timber biodiversity and carbon sequestration abstract fixed logging costs and administrative constraints on logging regulations can create nonconvexities in forestry production sets that include timber and nontimber products managing forests to produce multiple values at a landscape level through the aggregation of stands that are completely or partially specialized in the production of timber or nontimber products can consequently be superior to management systems that treat all stands uniformly even when all stands are identical both fixed costs and administrative constraints are empirically important sources of nonconvexity in tropical rainforests the former is more important when the nontimber product is carbon sequestration while the latter is more important when the nontimber product is biodiversity protection uniform management appears to be superior for the joint production of timber and carbon sequestration while specialized management might often be superior for the joint production of timber and biodiversity at least at low discount rates

zero expenditures and the estimation of engel curves over the brief interview periods typical of budget surveys such as the u k family expenditure survey households recorded expenditures are liable to be misleading indicators of their underlying consumption most starkly a household may not be observed to purchase commodities that it nevertheless consumes this paper considers the implications of such measurement errors for the estimation of demand systems and derives a consistent estimator for the special case of linear engel curves

using economic analysis in health workforce policy making the health workforce is an essential component in building responsive and efficient health care systems yet despite its importance it remains in many countries the weakest building block of the health system and a major constraint to achieving universal health coverage goals most countries face either absolute shortages not enough health workers or relative shortages skills imbalances sometimes both countries also face maldistribution inadequate training capacity and a weak knowledge base negative work environments weak human resources management systems poor working conditions and inadequate financial and non financial incentives there is growing consensus among researchers practitioners and the research community that many of these problems have labour market roots this paper reviews the main economic issues around key health workforce challenges and discusses the contributions that economic analysis can make to health workforce policy making it adopts a labour market framework to address the service delivery challenges countries face due to health workforce bottlenecks and discusses the importance and contribution of the health workforce to general employment and economic growth the use of an explicit economic framework helps to define policy responses that go beyond scaling up health workers training highlighting the importance also of the roles of incentives preferences and market failures

spatial distribution of species populations relative economic values and the optimal size and number of reserves we examine the tradeoff between the number and average size of nature reserves when the costs of enforcing reserve boundaries are negligible we find analytically that the relative price of biodiversity has a positive impact on the optimal total reserved area but an ambiguous impact on the optimal number of reserves simulation modeling of floral diversity in a tropical timber concession reveals that the resolution of this ambiguity depends on spatial distributions of the populations of tree species whether or not they are spatially aggregated clumped the impact of biodiversity price on optimal reserve number remains analytically ambiguous when enforcement costs are not negligible multiple reserves being economically superior to a single reserve now requires in addition to aggregation a biodiversity price that is sufficiently high to offset the effects of enforcement costs most of our simulation scenarios generate threshold biodiversity prices that do not exceed a leading estimate of the marginal value of a higher plant species in the bioprospecting literature several smaller reserves evidently can be economically superior to a single larger one even in the presence of enforcement costs

methods of household consumption measurement through surveys experimental results from tanzania consumption expenditure has long been the preferred measure of household living standards however accurate measurement is a challenge and household expenditure surveys vary widely across many dimensions including the level of reporting the length of the reference period and the degree of commodity detail these variations occur both across countries and also over time within countries there is little current understanding of the implications of such changes for spatially and temporally consistent measurement of household consumption and poverty a field experiment in tanzania tests eight alternative methods to measure household consumption on a sample of 4 000 households there are significant differences between consumption reported by the benchmark personal diary and other diary and recall formats under reporting is particularly relevant in illiterate households and for urban respondents completing household diaries recall modules measure lower consumption than a personal diary with larger gaps among poorer households and households with more adult members variations in reporting accuracy by household characteristics are also discussed and differences in measured poverty as a result of survey design are explored the study concludes with recommendations for methods of survey based consumption measurement in low income countries

policy relevant nonconvexities in the production of multiple forest benefits abstract this paper challenges common assumptions about convexity in forest rotation models which optimize timber plus nontimber benefits if a local optimum occurs earlier than the globally optimal age policy based on marginal incentives may achieve suboptimal results policy relevant nonconvexities are more likely if i nontimber benefits dominate for young stands while the optimal age depends primarily on timber benefits or ii nontimber benefits dominate for mature stands and also determine the optimal age nonconvexities may create either temporary or persistent difficulties policymakers may improve efficiency by exploiting the relationship between the timber only optimum and the global optimum

spatial interactions in multiple use forestry and substitution and wealth effects for the single stand abstract forestry models often ignore spatial relationships between forest stands this paper isolates the effects of stand interactions in multiple use forestry through a straightforward extension of the single stand model effects of stand interactions decompose into wealth and substitution effects and may cause time varying patterns of resource use for a forest stand simulations illustrate that a stand s role even in steady state may alternate an emphasis on timber with an emphasis on nontimber optimal management plans differ substantially depending on whether the manager values nonmarket goods from neighboring stands the model offers insights for improving heuristic forest level optimization models in current usage

estimating consumption from expenditure data abstract most studies of distributional issues have focused on the distribution of income but the income information usually available suffers from well known deficiencies this paper explores an alternative approach to distributional analysis based instead on expenditure data in many countries including the united kingdom available household budget data provides information on expenditures only over a short period the problems that consequently arise in interpreting data of this sort are emphasised a general specification for the stochastic structure of expenditure data is presented and a procedure for estimating participant households underlying consumption from their observed expenditures developed and discussed

testing the infrequent purchases model using direct measurement of hidden consumption from food stocks survey reports of zero expenditure result from either genuine non consumption or purchases undertaken too infrequently to observe during a survey with hidden consumption from stocks infrequent purchase models rely on untested hypotheses to distinguish these types of zeros we test such models with data from an unusual survey where food stocks are measured at the start and end of the survey reference period parameter estimates using these direct measures of hidden consumption out of stocks are compared with estimates from infrequent purchase models that attempt to recover this hidden consumption the results suggest considerable bias when using the infrequent purchase models copyright 2012 oxford university press

differences and similarities between ecological and economic models for biodiversity conservation abstract in this paper we investigate an important obstacle which substantially complicates co operation between ecologists and economists but which has received little attention so far differences between the modelling approaches in economics and ecology to understand these differences 60 models addressing issues relevant to biodiversity conservation have been selected randomly from eight international economic and ecological journals the models have been compared according to a number of criteria including the models level of generality the mathematical techniques employed for formulation and solution of the models the level of complexity and the way time space and uncertainty are taken into account the economic models sampled are formulated and analysed analytically tend to be relatively simple and are mostly used to investigate general questions furthermore they often ignore space dynamics and uncertainty although some ecological models have similar properties there is also a substantial number of another type of ecological models that are relatively complex and analysed by simulation these models tend to be rather specific and often explicitly consider dynamics space and uncertainty the integrated ecological economic models are observed to lie in the middle between ecological and economic models an unexpected result is that they are not more complex than ecological and economic models as one could have expected from a simple merger of models from both disciplines but have an intermediate complexity

rent capture and the feasibility of tropical forest management hyde amacher and magrath 1996 imply that deforestation and timber rents logging revenue minus logging costs other than timber fees are not subjects that justify policymakers attention arguing that market responses limit the scope of deforestation

the impact of tax reforms designed to encourage healthier grain consumption in this paper we simulate the effects of tax reforms aimed at encouraging healthier grain consumption we use a rich data set on household grain consumption in 2003 from the market research institute gfk sweden combined with information on the nutritional content of the consumption we estimate behavioral parameters which are used to simulate the impact on the average household of tax reforms entailing either a subsidy on commodities particularly rich in fiber or a subsidy of the fiber density in grain products our results suggest that to direct the fiber intake towards nutritional recommendations reforms with a substantial impact on consumer prices are required regardless of the type of subsidy implemented the increase in the intake of fiber is accompanied by unwanted increases in nutrients that are often overconsumed fat salt and sugar funding the subsidies by taxing these nutrients or less healthy commodities helps to counteract such developments

efficient multiple use forestry may require land use specialization considered at the landscape scale economically efficient multiple use of forests may require land use specialization if managers attempt to satisfy legitimate multiple use demands from society by managing all lands for all outputs both commodity and amenity values of the forest may be inappropriately supplied and management inputs may be inefficiently deployed these results run counter to some of the prescriptions called new forestry

targeting incentives to reduce habitat fragmentation the fragmentation of wildlife habitat has long been recognized as a principal threat to terrestrial biodiversity in this paper we develop a theoretical model to analyze the spatial targeting of incentives for the restoration of forested landscapes when land quality is spatially heterogeneous and wildlife habitat can be enhanced by reducing fragmentation we consider a regulator who uses subsidies to encourage the conversion of private agricultural land to forest on a pre defined set of landscapes the regulator can observe land use choices but not the opportunity costs on individual land parcels the important insight to emerge from the theoretical analysis is that solutions at or near corners are a strong possibility on each landscape either none or all of the agricultural land should be converted to forest corner solutions are directly linked to the spatial process determining habitat benefits to verify the theoretical insight we present a simulation of the effects of incentive based policies on the spatial distribution of forests in south carolina the empirical methodology integrates an econometric model of land use change with gis based landscape simulations the empirical findings strongly support our conjecture regarding corner solutions and the optimal targeting policy is shown to produce substantial welfare gains over a spatially uniform incentive

environmental efficiency and labour productivity trade off or joint dynamics a theoretical investigation and empirical evidence from italy using namea in this paper we test an adapted ekc hypothesis to verify the relationship between environmental efficiency namely emissions per unit of value added and labour productivity value added per employee we exploit namea data on italy for 29 sector branches and 6 categories of air emissions for the period 1991 2001 we employ data on capital stock and trade openness to test the robustness of our results on the basis of the theoretical and empirical analyses focusing on innovation firm performances and environmental externalities we would expect a positive correlation between environmental efficiency and labour productivity a negative correlation between the emissions intensity of value added and labour productivity which departs from the conventional mainstream view the hypothesis tested is a critical one within the longstanding debate on the potential trade off or complementarity between environmental preservation and economic performance which is strictly associated with the role of technological innovation we find that for most air emission categories there is a positive relationship between labour productivity and environmental efficiency labour productivity dynamics then seem to be complementary to a decreasing emissions intensity in the production process taking a disaggregate sector perspective we show that the macro aggregate evidence is driven by sector dynamics in a non homogenous way across pollutants services tend always to show a complementary relationship while industry seems to be associated with inverted u shape dynamics for greenhouse gases and nitrogen oxides this is in line with our expectations in any case ekc shapes appear to drive such productivity links towards complementarity the extent to which this evidence derives from endogenous market forces industrial and structural change and policy effects is discussed by taking an evolutionary perspective to innovation and by referring to impure public goods arguments

statistical models for zero expenditures in household budgets household budget surveys are an important source of data on consumer s expenditure not just for individual consumers but also for estimating national aggregates however it is a widespread finding that for certain commodities most notably tobacco and alcohol the estimate from the household survey falls short of the known consumption total calculated with some confidence from data on production imports exports and excise duties for example in the british family expenditure survey with which we shall largely be concerned total tobacco expenditure was underestimated in 1976 by 21 percent see kemsley redpath and holmes 1980 p 51 much of this understatement together with that on alcohol is thought to occur because of the design of the survey which excludes many persons amongst whom consumption of such items is thought to be atypically high e g prisoners hoteliers and their residents merchant seamen even so the possibility remains that some of the understatement is due to various types of misreporting by households included in the survey in this paper we consider a model in which the standard tobit specification tobin 1958 is supplemented by the operation of a simple binary censor the tobit model is essentially a linear regression model in which non positive observations of the dependent variable are replaced by zero we take this specification as our starting point but add a second censoring process that randomly replaces a fraction of the observations generated by the tobit model bv zeroes the combined model can serve as a representation of several types of

distinguishing between market participation and infrequency of purchase models of butter demand household butter expenditures are modeled by market participation and infrequency of purchase specifications the market participation model assumes that zero expenditures represent either traditional corner solutions or consumers who never use the product whereas the infrequency of purchase model assumes that zero expenditures represent either corner solutions or consumption out of storage we determine that the infrequency of purchase specification is preferred to the market participation model by applying a nonnested test based upon likelihood functions if household expenditure surveys contained information about participation and frequency of purchase a likelihood function which contained both models could be written and estimated

a regional dynamic general equilibrium model of alternative climate change strategies outcomes and noncooperative equilibria this study finds that cooperative policies show much higher levels of emissions reductions than do noncooperative strategies that there are substantial differences in the levels of controls in both the cooperative and the noncooperative policies among different countries and that high income countries may be the major losers from cooperation jel h41 q4 q2 q20

opportunity cost estimation of ecosystem services land use changes rank among the most significant drivers of change in ecosystem services worldwide the enhancement of important services such as biodiversity and carbon sequestration requires modifications in land use that can lead to the decline in other ecosystems services targeting the most suitable areas for particular land uses based on comparative advantages requires opportunity cost information across large regions this is a demanding task because the input output relations are ill defined and determined by spatially heterogeneous operational and environmental conditions to address this methodological challenge this paper presents a two stage semiparametric technique that enables multi dimensional production possibility frontiers to be estimated from data provided by biophysical models specific advantages of the proposed frontier approach are its flexibility with regard to assumptions on the convexity of the production possibility set and its freedom from any separability assumptions for the input output space and the space of the heterogeneous background variables the method is illustrated for a case study of 18 central and eastern european countries results show that opportunity costs of changes in ecosystem services provision differ substantially between regions those areas having already relatively high levels of carbon sequestration have a comparative advantage in sequestering carbon opportunity costs of biodiversity are generally positively related with the level of biodiversity up to a turning point after which they are negatively related to illustrate the policy consequences of the observed economies and diseconomies of scope we compare two management regimes to illustrate the potential gains from smart land management