reflections on the nature and policy implications of planning restrictions on housing supply discussion of planning policy planning practice and housing supply by kate barker planning is about other things as well but it is fundamentally an economic activity it allocates a scarce resource but independently of prices or any market information in analysing the effects this allocative mechanism has on housing supply or indeed the supply of buildings for any given use we need to think carefully about what exactly it is that planning allocates and whether in its operation it creates a constraint on the supply of what it is allocating in the british case our planning system does not operate on the supply of housing directly but indirectly via the constraint imposed on land supply given the income elasticity of demand for space this has policy implications perhaps even more serious than is acknowledged by barker

the introduction of price signals into land use planning decision making a proposal although directed to the british system of town and country planning this paper has relevance for many oecd countries including some with systems of land use regulation which evolved entirely independently of the british the paper starts by characterising the basic features of the british land use planning system viewed from the resource allocation point of view of an economist a conclusion is that the system explicitly excludes any use of price signals from its decisions the paper then summarises the problems which the exclusion of price information has given rise to because the uk planning system has deliberately constrained the supply of space and space is an attribute of housing which is income elastic in demand rising incomes not only drive rising real house prices but also mean that land prices have risen considerably faster than house prices several housing attributes other than garden space are to a degree substitutes for land but the underlying cause of the inelastic supply of housing in the uk is the constraint on land supply the final section proposes a mechanism which would make use of the information embodied in the price premiums of neighbouring parcels of land zoned for different uses such premiums signal the relative scarcity of land for different uses at each location and should become a material consideration in planning decision making if they were above some threshold this should provide a presumption of development unless maintaining the land in its current use could be shown to be in the public interest if combined with impact fees such a change would not only make housing supply more elastic and the system more transparent but would help to distance land availability decisions from the political process

metabolic inequality and its impact on efficient contraction and convergence of international material resource use international inequality in material use decreased between 1970 and 2000 inequality stabilized 2000 to 2010 when global growth in material use accelerated material intensity has gained importance in shaping material use inequality inequality in material intensity has increased and shapes global material use

new urbanism and housing values a disaggregate assessment in this paper we attempt a formal analysis of the virtues of new urbanism a movement hailed as the most significant movement in urban planning and architecture in this century we proceed using the tools of geographic information systems gis to develop quantitative measures of urban form we then incorporate those measures in a hedonic price analysis we find that our measures of urban form capture meaningful differences in the characters of urban neighborhoods that could well have direct impacts on the utility of urban residents further we find that such differences are capitalized into residential property values the results imply that some but not all of the design features of new urbanism provide benefits for which urban residents are willing to pay

international inequalities in per capita co2 emissions a decomposition methodology by kaya factors in this paper we provide a methodology for decomposing international inequalities in per capita co2 emissions into kaya multiplicative factors and two interaction terms we use the theil index of inequality and show that this decomposition methodology can be extended for analyzing between and within group inequality components we can thus analyze the factors behind inequalities in per capita co2 emissions across countries between groups of countries and within groups of countries the empirical illustration for international data suggests some points firstly international inequality in per capita co2 emissions is mainly attributable to inequalities in per capita income levels which helps to explain its recent reduction while differences in carbon intensity of energy and energy intensity have made a less significant contribution this result is strongly influenced by the performance of china and india secondly the between group inequality component which is the biggest component is also largely explained by the income factor thirdly the within group inequality component increased slightly during the period something mainly due to the change in the income factor and the interaction terms in a few regions

global patterns of metal extractivism 1950 2010 providing the bones for the industrial society s skeleton during the second half of the 20th century mining expanded globally and must be considered one of the dominant forms of human intervention into the environment metals are strategically important resources for industrialized and industrializing societies in 2010 the five brics countries brazil the russian federation india china and south africa consumed 54 of the metals mined globally the analysis of material flow data offers a biophysical perspective on mining as a resource frontier and allows for the identification of patterns in global metals extraction and trade since 1950 metal extraction has shifted from the early industrializing countries into the emerging economies in 2010 only 6 of metals mined stemmed from europe or north america while 76 were extracted in four countries australia china india and brazil in the countries hosting large scale mining operations socio ecological pressure ensues the so called extractivist development path is common high rates of metal deposit depletion mean that today s metal extractors and exporters may depend on imports of metal from anthropogenic deposits stocks in buildings infrastructure and durable products in the future the extractivist path and the shifting of metals from natural to anthropogenic deposits are both associated with potential for conflict

distributional aspects of emissions in climate change integrated assessment models the recent failure of copenhagen negotiations shows that concrete actions are needed to create the conditions for a consensus over global emission reduction policies a wide coalition of countries in international climate change agreements could be facilitated by the perceived fairness of rich and poor countries of the abatement sharing at international level in this paper i use two popular climate change integrated assessment models to investigate the path and decompose components and sources of future inequality in the emissions distribution results prove to be consistent with previous empirical studies and robust to model comparison and show that gaps in gdp across world regions will still play a crucial role in explaining different countries contributions to global warming

estimation of censored demand equations from large cross section data the article develops an alternative econometric methodology to estimate a system of censored demand equations using a large cross section data from colombian urban households the approach preserves the behavioralinformation expressed by zero expenditures and conforms with the requirements imposed by consumer theory in a way consistent with the random utility hypothesis we motivate the choice of the tobit modelas a statistical representation of consumer behavior and introduce the methodology by specifying the aids model modified according to both a translating and scaling demographic transformation we propose to estimate each demand equation in unrestricted form using the jackknife technique we then recover the demand parameters imposing the cross equations restrictions by using minimum distance estimation the empirical results of the censored demand system for specific households of policy relevance are reported copyright 2000 oxford university press

trade environment and development the issues in perspective abstract this special issue on trade and the environment brings together a number of papers that are constructively critical of the conventional economic wisdom on the topic we think that this criticism is warranted because of the decidely uncritical way in which free trade has been advocated in much of the literature and especially in policy the papers analyse the validity of the underlying assumptions on which the conventional wisdom is based and provide suggestions for ways to facilitate trade that is also adequately protective of the environment sustainability and other social values in this introductory piece we discuss trade the environment and sustainability summarizing arguments in the papers included in this issue and adding a few additional points not covered by them

ecological macroeconomics in the open economy sustainability unequal exchange and policy coordination in a center periphery model abstract this article introduces a novel environmental interpretation of a keynesian coordination game and develops four potential scenarios to remaining within a global carbon emissions constraint with inspiration from research on ecologically unequal exchange eue we demonstrate the drawbacks of present green growth strategies by considering how pollution and resource intensive industries are distributed unevenly in the world economy with large and increasing negative impacts on the periphery the situation may only be exacerbated if the reduction of emissions in the center is based on shifting heavy industries and extractive enterprises to low cost producers in the periphery in this way existing research likely overemphasizes the capacity of green investment policy to achieve sustainable outcomes our scenarios show that achieving global sustainability and improving global equity will require an impressive level of coordination between the center and periphery as well as a significant reduction in the rate of growth degrowth in the center

global appropriation of resources causes high international material inequality growth is not the solution abstract high levels of resource consumption cause detrimental environmental change very low consumption may fail to meet basic needs a major challenge for a sustainability transformation is to reduce inequalities and achieve a globally sustainable level of resource flows by providing access to resources beyond national boundaries trade could either lead to more equal international distribution or aggravate unequal distribution of material resources for a sample of 173 countries between 1993 and 2010 we studied the role of trade and the upstream global appropriation of resources in international material inequality until the turn of the century per capita material extraction was as unequally distributed as material consumption extraction plus imports minus exports import and export flows as such do not greatly affect inequality the global appropriation of materials associated with trade however decisively increased inequality until 2000 in the 21st century decreasing inequality coincided with a sharp rise in global material extraction appropriated by high and upper middle income countries such growth led reduction of inequality is not environmentally sustainable it has until now been enabled by global trade patterns distributing resources in a way that can never be globally inclusive putting especially the world s poorest countries at risk

recovering individual preferences for non market goods a collective travel cost model traditional recreation demand models do not make a distinction between a household and an individual as the reference decision making unit thus assuming that a family maximizes a single utility function even if the family consists of different individuals such models ignore the possibility of family members divergent preferences for non market goods this study proposes a novel approach the collective travel cost model ctcm to eliciting individual preferences for a non market good such as a recreation site by using revealed preference data this approach accounts for the intra household resource allocation and the role of each household member s preferences we show that the collective travel cost model can be applied to estimating a recreation demand model that yields individual welfare estimates appropriate for policy analysis of non market goods such as the willingness to pay to access a recreation site we find that how resources are distributed within the household reflects significant differences in welfare measures

food demand in mexico an application of the amemiya tobin approach to the estimation of a censored food system the modeling of micro level food demand patterns requires not only allowing for household heterogeneity but also addressing the problem of censoring in this article we present a variation of the amemiya tobin framework for estimating a censored demand system that allows for household heterogeneity the unique aspect of our approach is the use of a procedure that ensures the adding up of both latent and observed expenditure shares and also imposes expenditure share nonnegativity this system is applied to an analysis of food demand based on a random sample of urban mexican households

disaggregated household meat demand with censored data previous research on meat demand has generally used highly aggregated data across time products and consumers however meat products across species are likely stronger substitutes than some products from the same species further demand for specific meat products would be expected to respond differently to market information about food safety or other events this study uses monthly consumer panel data collected between 1992 and 2000 to estimate a disaggregated meat product demand system the use of the expectations maximization algorithm is introduced to estimate a demand system that adjusts for the econometric problem of censored data resulting from purchased shares of some products by individuals often being equal to zero results indicate that certain individual meat products have noticeably different own price elasticities than existing aggregate meat product estimates of their respective species some individual meat products have stronger substitutes across species than within species e g be

estimation of demand functions using cross sectional household data the problem revisited a procedure that corrects for selectivity bias is proposed to estimate demand functions using cross sectional data under the assumption that prices vary across households this procedure which extends the work by cox and wohlgenant includes a two equation system of expenditure and unit value functions this model is applied to household expenditures for beef steaks and roasts

structural agricultural land use modeling for spatial agro environmental policy analysis this paper develops a spatially disaggregated structural econometric model of agricultural land use and production based on the joint multi output technology representation introduced by chambers and just 1989 starting from a flexible specification of the farm profit function we derive land use allocation input application crop yield and livestock intensity equations in a joint and theoretically consistent framework to account for the presence of censored observations in micro level data the model is estimated as a system of two limit tobit equations via quasi maximum likelihood we present an empirical application using fine scale spatial data covering the entirety of england and wales and including the main economic policy and environmental drivers of land use change in the past forty years a simulation of the effects of diffuse pollution reduction measures illustrates how our approach can be applied for agro environmental policy appraisal

the politics of land supply and affordable housing auckland s housing accord and special housing areas increasingly planning for housing development involves political conflict between local government planning practices based on urban sustainability and housing intensification and central government housing policies centred on land supply and housing affordability this paper examines a key historical moment in the politics of housing supply and planning in new zealand drawing upon a discourse analysis of a range of housing policy documents and urban plans this paper traces the dynamic of local and central government negotiations and conflict arising from the development of auckland s spatial plan the development of the auckland housing accord a central and local government agreement to fast track planning permission for new housing and the implementation of the housing accords and special housing areas act the paper focuses on the manner in which certain policy knowledge is prioritised and applied in the construction of affordable housing policies and how this process which is presented as obj

the welfare economics of land use planning abstract this paper presents an empirical methodology for the evaluation of the benefits and costs of land use planning the technique is applied in the context of the town and country planning system of the uk and examines the gross and net benefits of land use regulation and their distribution across income groups the results show that the welfare and distributional impacts can be large

inequality in co2 emissions across countries and its relationship with income inequality a distributive approach this paper analyses the inequality in co2 emissions across countries and groups of countries and the relationship of this inequality with income inequality across countries for the period 1971 1999 the research employs the tools that are usually applied in income distribution analysis the methodology used here gives qualitative and quantitative information on some of the features of the inequalities across countries that are considered most relevant for the design and discussion of policies aimed at mitigating climate change the paper studies the relationship between co2 emissions and gdp and shows that income inequality across countries has been followed by an important inequality in the distribution of emissions this inequality has diminished mildly although the inequality in emissions across countries ordered in the increasing value of income inequality between rich and poor countries has diminished less than the simple inequality in emissions lastly the paper shows that the inequality in co2 emissions is mostly explained by the inequality between groups with different per capita income level the importance of the inequality within groups of similar per capita income is much lower and has diminished during the period especially in the low middle income group

habit formation and demand for sugar sweetened beverages using scanner data we estimated demand for nine nonalcoholic beverages under habit formation we found strong evidence for habit formation although demand for sugar sweetened beverages by low income households is less elastic to own price changes compared with high income households there is evidence that high income households consider beverages to be more substitutable than low income households do a half cent per ounce tax on store purchased sugar sweetened beverages will result in a moderate reduction in consumption of sugar sweetened beverages for both income strata because of habit formation long run national tax revenue from a sugar sweetened beverage tax is about 15 to 20 lower than short run revenue

the high price of dematerialization a dynamic panel data analysis of material use and economic recession abstract dematerialization at the national level occurs almost exclusively during periods of economic recession or low growth while recession is not a sustainable strategy to curb environmental impact such periods may offer important insights on the possibilities of reducing material use economic recession research has focused on the interactions between macroeconomic and financial variables with little systematic research dedicated to uncovering how resource use develops during periods of recession using a dynamic panel model we investigate whether and to what extent material use in a sample of 150 economies between 1970 and 2010 was affected by recession and low growth recession occurred most frequently and in more than two thirds of all countries during the 1980s and the 1990s in the 2000s more than half of the recessions occurred during the financial crisis of 2008 periods of recession were significantly and negatively correlated with material use they tended to coincide with dematerialization material use decreased in recession years but the significant correlations with growth in material use became weaker as growth rates increased construction minerals and metals used to build stocks of manufactured capital reacted more strongly to economic fluctuations than the throughput dominated flows of biomass and fossil fuels we conclude that the systematic link between recession and dematerialization can become policy relevant if the mechanisms causing reductions in material use during these periods are identified

trade and the environment from a southern perspective the relationship between free trade and the environment is one of the main issues of contention between environmental and ecological economics environmental economics assumes a positive relationship between free trade economic growth and environmental policies environmental externalities may cause important damage however trade is not to be blamed for this instead the fault lies with policy inadequacies at the national level on the other hand some ecological economists criticise the assumptions of environmental economics especially the immobility of production factors and the positive correlation between income and environmental quality they plead for measures to prevent deterioration of northern environmental standards in a race to the bottom due to ecological dumping from the south in this paper we argue that neither environmental economics nor northern ecological economics take into account the structural conditions determining the international trade system based on some new empirical evidence on material flows we stress the notion of environmental cost shifting if physical and political ecology perspectives are adopted a southern approach to the trade and environment issue may arise 2001 elsevier science b v all rights reserved

a theory of land prices when land is supplied publicly the case of the netherlands most attempts to explain land prices assume free competition between suppliers and demanders of land if there are constraints on this competition e g land use planning this is added as a modification to the theory when however the supply of building land is in the hands of public agencies which determine the volume and price of supply specified by land use and location a different theoretical approach is needed in this situation certain economic principles apply which determine the maximum and minimum prices at which land will be bought for development and at which serviced building land will be supplied for development however both the limits of this range and the actual land prices within it will depend on political choices made by the public agencies in the netherlands municipalities dominate the supply of land for development and redevelopment information about the way dutch municipalities make the political choices and about the actual land prices there suggests they make the politic

planning policy planning practice and housing supply this paper outlines a brief history of planning policy in england as it relates to housing it discusses briefly the issues raised by a plan led system and the uncertainties of household projections evidence on the relationship between house prices and housing supply and on house builders landbanks suggests that planning constraints are a key factor behind the long term upward trend in house prices though over shorter periods other factors such as long term real interest rates will be more important it concludes that the environmental constraints on additional housing supply albeit important can be overstated while there are serious adverse social consequences of the way in which the english housing market works today it is not yet clear that the largely welcome policy steps taken over the past 3 years will prove sufficient to resolve this problem

economies of scale household size and the demand for food household scale economies are plausibly attributed to shared household public goods that make larger households better off at the same level of per capita resources larger households should therefore have higher per capita consumption of private goods such as food provided that they do not substitute too much toward the effectively cheaper public goods the evidence shows exactly the opposite data from rich and poor countries indicate that at constant per capita total expenditure the per capita demand for food decreases with household size and that it does so most in the poorest countries where substitution should be the least

efficient intra household allocations a general characterization and empirical tests the neoclassical theory of demand applies to individuals yet in empirical work it is usually taken as valid for households with many members this paper explores what the theory of individuals implies for households that have more than one member we make minimal assumptions about how the individual members of the household resolve conflicts all we assume is that however decisions are made outcomes are efficient we refer to this as the collective setting we show that in the collective setting household demands must satisfy a symmetry and rank condition on the slutsky matrix we also present some further results on the effects on demands of variables that do not modify preferences but that do affect how decisions are made we apply our theory to a series of surveys of household expenditures from canada the tests of the usual symmetry conditions are rejected for two person households but not for one person households we also show that income pooling is rejected for two person households we then test for our collective setting conditions on the couples data none of the collective setting restrictions are rejected we conclude that the collective setting is a plausible and tractable next step to take in the analysis of household behavior

the effects of male and female labor supply on commodity demands we examine the effects of male and female labor supply on household demands and present a simple and robust test for the separability of commodity demands from labor supply using data on individual households from six years of the uk fes we estimate a demand system for seven goods which includes hours and participation dummies as conditioning variables allowance is made for the possible endogeneity of these conditioning labor supply variables we find that separability is rejected furthermore we present evidence that ignoring the effects of labor supply leads to bias in the parameter estimates

global patterns of materials use a socioeconomic and geophysical analysis abstract human use of materials is a major driver of global environmental change the links between materials use and economic development are central to the challenge of decoupling of materials use and economic growth dematerialization this article presents a new global material flow dataset compiled for the year 2000 covering 175 countries including both extraction and trade flows and comprising four major material categories biomass construction minerals fossil energy carriers and ores industrial minerals first we quantify the variability and distributional inequality gini coefficients in international material consumption we then measure the influence of the drivers population gdp land area and climate this analysis yields international income elasticities of material use finally we examine the coupling between material flows and between income and material productivity measured in economic production per tonne material consumed material productivity is strongly coupled to income and may thus not be suitable as an international indicator of environmental progress a finding which we relate to the economic inelasticity of material consumption the results demonstrate striking differences between the material groups biomass is the most equitably distributed resource economically the most inelastic and is not correlated to any of the mineral materials the three mineral material groups are closely coupled to each other and economic activity indicating that the challenge of dematerializing industrial economies may require fundamental structural transformation our analysis provides a first systematic investigation of international differences in material use and their drivers and thus serves as the basis for more detailed future work

international ecological footprint inequality a methodological review and some results scarcities of environmental services are no longer merely a remote hypothesis consequently analysis of their inequalities between nations becomes of paramount importance for the achievement of sustainability this paper aims on the one hand at revising methodological aspects of the inequality measurement of certain environmental data and on the other at extending the scarce empirical evidence relating to the international distribution of ecological footprint ef most of the techniques currently important in the literature are revised and then tested on ef data with interesting results we consider the underlying properties of different inequality indices those indices which fit best with environmental inequality measurements are cv 2 and ge 2 because of their neutrality property subgroup and source decompositions are also discussed from a methodological perspective empirically this paper contributes to the environmental inequality measurement of ef this inequality has been quite stable subgroup decomposition by using exogenous country groups world bank classification conclude that between group inequality explains almost the totality of international ef inequality source decomposition warns of the dangers of confining co 2 emissions reduction to crop based energies because of the implications for basic needs satisfaction

ossified materialism introduction to the special volume on absolute reductions in materials throughput and emissions drawing from papers in this special volume sv this introductory paper on absolute reductions argues that the magnitude scope and urgency of the sustainability challenge require a drastic change in global civilisation including a radical transformation of the institutional arrangements and socio technical systems that facilitate the pursuit of wellbeing the authors of this paper identify four main challenges to absolute reductions including the resource intensive conventional template for development macroeconomic structures and trade policies creating burden shifting and inequality a resourceefficiency improvements fallacy and the dominant consumerist culture and lifestyles the paper demonstrates

changing household characteristics and the away from home food market a censored equation system approach abstract the american consumer is obtaining more and more of his or her food at a restaurant and that worries some people concerned with the nation s dietary health to date much of this concern seems to be directed at the fast food segment of the restaurant industry this paper asks whether targeting one segment of the industry such as fast food restaurants is justified or whether a more balanced view of eating away from home is required to answer this question we look to the future and ask whether americans can be expected to purchase increasingly more fast food or more and more of the foods typically associated with full service dining one view is that sales at full service restaurants will now grow relatively faster than sales of fast food the argument supporting this position rests on rising incomes the aging of the population smaller household sizes and other changes taking place in the population using a new full information maximum likelihood procedure for estimating a system of censored expenditure equations we find evidence to support this argument

the second engel law is it a paradox abstract the second engel law says that the engel curve for food moves out as family size increases thus showing a decrease in welfare what is puzzling though is that this regularity does not hold for equivalent income functions expressed in per capita terms deaton and paxon 1998 economies of scale household size and the demand for food journal of political economy 106 5 897 930 show that holding per capita total household expenditure constant per capita expenditure on food falls with the number of heads deaton and paxson s empirical evidence from developed and less developed countries seems to invalidate the claim of the second engel s law the main objective of this paper is to understand such paradoxical relationship between food consumption and household size our nonparametric empirical evidence drawn from the colombian 1985 urban survey shows that the food share is negatively related to total household per capita expenditure in line with deaton and paxson s claim but equivalent incomes shift to the right as theory predicts the regularity of our nonparametric results is an indication of a problem in the parametric specification of the engel curve modified by family size in fact using also the surveys of italy nepal djibouti and bangladesh we show that a theoretically plausible modified engel curve is coherent with the claim of the second engel law and explains deaton and paxson s paradox

investment choice and asset allocation of italian households the discrete continuous approach financial and monetary policies are considered to be effective depending on the reaction of financial markets which are increasingly populated by households in this article from intertemporal settings i derive a financial almost ideal fai demand system and i estimate it by highlighting the determinants of both limited participation to financial markets and asset substitutability complementarity in the allocating stage finally the wealth elasticities provide some further insights on the low diffusion of the newer and more complex financial instruments across italian households

semiparametric estimation of consumer demand systems with micro data maximum likelihood and two step estimators of censored demand systems yield biased and inconsistent parameter estimates when the assumed joint distribution of disturbances is incorrect this paper proposes a semiparametric estimator that retains the computational advantage of the two step approach but is immune to distributional misspecification the key difference between the proposed estimator and the two step estimator is that the parameters of the binary censoring equations are estimated using a distribution free single index model we implement the proposed estimator using household level data obtained from the hainan province in china specification test lends support to our approach

global income distribution from the fall of the berlin wall to the great recession we present an improved panel database of national household surveys between 1988 and 2008 in 2008 the global gini index is around 70 5 having declined by approximately 2 gini points china graduated from the bottom ranks changing a twin peaked global income distribution to a single peaked one and creating an important global median class 90 of the fastest growing country deciles are from asia while almost 90 of the worst performers are from mature economies another winner was the global top 1 hence the global growth incidence curve has a distinct supine s shape with gains highest around the median and top

assessing the accessibility of the homeownership market in this paper an examination is made of the accessibility of the homeownership market using measures that include both supply and demand characteristics of regional housing markets these measures are applied empirically on an extensive dataset that covers the dutch housing market the analysis quantifies the extent to which the position of first time buyers on the homeownership market has weakened over time and identifies the driving factors of this change it is found that smaller portions of the housing market are becoming affordable due to financial constraints of young households however more importantly first time buyers today need to contend with a much larger group of competing bidders on every house that suits their financial situation than ever before

what do we learn about consumer demand patterns from micro data the aim of this paper is to assess the importance of using micro level data in the econometric analysis of consumer demand to do this we utilize a time series of repeated cross sections covering some 4 000 households in each of 15 years employing a number of different aggregation procedures we conclude that aggregate data alone are unlikely to produce reliable estimates of structural price and income coefficients however once certain aggregation factors as well as trend and seasonal components are included an aggregate model is not necessarily outperformed across all demand equations in terms of forecasting ability jel d12 c52 c31 the purpose of this paper is to develop a complete consumer demand system based on a time series of individual household data and to use it to measure the biases introduced into the study of consumer de mand behavior when aggregate data are used in place of the appropriate microeco nomic data we assess the suitability of ag gregate data through the impact on income and price elasticities and by evaluating the ability of both micro and aggregate based models to forecast aggregate consumer de mand the biases introduced by the use of aggregate data depend upon the way that household characteristics interact with in come and price effects and on departures of demand systems from linearity we explore the structure of microeconomic demand sys tems and the role of household characteris tics in the behavior of consumer demand both for the light this may shed on the pattern of future demands and for the im plications this behavior has for issues of aggregation consumer demand patterns typically found in micro data sets vary considerably across households with different household characteristics and with different levels of income we model this variability by making intercept and slope parameters in the budget share equations of our demand sys tem depend on household characteristics and by allowing for nonlinear total log expenditure terms in fact in theory consistent demand systems it is total ex penditure rather than disposable income that is allocated across goods we find that this general framework leads to a well specified data coherent demand system which is a quadratic extension of the popu lar almost ideal model of angus s deaton and john muellbauer 1980 the micro level estimates are shown to be sensitive to the treatment of endogeneity of total expen diture and to the specification of interaction terms with household characteristics in ad dition this specification is also shown to possess many attractive features for the evaluation of aggregate models