designing supply contracts contract type and information asymmetry this paper studies the value to a supplier of obtaining better information about a buyer s cost structure and of being able to offer more general contracts we use the bilateral monopoly setting to analyze six scenarios three increasingly general contracts wholesale pricing schemes two part linear schemes and twopart nonlinear schemes each under full and incomplete information about the buyer s cost structure we allow both sides to refuse to trade by explicitly including reservation profit levels for both for the supplier this is implemented through a cutoff policy we derive the supplier s optimal contracts and profits for all six scenarios and examine the value of information and of more general contracts our key findings are as follows first the value of information is higher under two part contracts second the value of offering two part contracts is higher under full information and third the proportion of buyers the supplier will choose to exclude can be substantial

order quantity and timing flexibility in supply chains the role of demand characteristics we study how differences in product demand characteristics affect the strategic value of different types of supply chain flexibility for accurate response we propose a single period inventory modelling framework with two ordering opportunities the second order reflects updated demand information and potentially capitalizes on supply chain flexibility we consider two complementary forms of flexibility quantity flexibility in production and timing flexibility in scheduling in this framework we analyze the total inventory cost of a firm for alternate demand types we model functional products through the standard assumption of independent demand over the period fashion driven innovative products through a bayesian model and innovative products with evolving demand through a martingale process the three demand processes exhibit very different behavior with respect to the value of the alternate forms of flexibility we observe that quantity flexibility is of moderate value for functional goods and of high value for fashion driven products for all lead times quantity flexibility is of low value for goods with evolving demand with long lead times but of high value for short lead times alternately we observe timing flexibility is of highest value for functional goods especially for cases of high holding cost and is of lesser value for fashion driven goods it is of least value for goods with evolving demand both quantity and timing flexibility capabilities are required to significantly reduce the relevant supply chain costs for evolving demand innovative goods when the lead times are long

monopoly pricing with negative network effects the case of vaccines abstract we study the market for vaccinations considering income heterogeneity on the demand side and monopoly power on the supply side a monopolist has an incentive to exploit the external effect of vaccinations and leave the poor susceptible in order to increase the willingness to pay the rich even the possibility of price discrimination does not remove this incentive we demonstrate that the weaknesses of standard policy measures are mitigated when income heterogeneity is taken into account this offers an efficiency based rationale for distribution oriented national or international public health interventions

inventory control under temporal demand heteroscedasticity abstract this paper studies an inventory control problem when the variance of demand is time varying and exhibits temporal heteroscedasticity we use a first order autoregressive process to characterize the dynamic changes in the level of demand over time and a garch 1 1 structure to describe the changes in the variance of demand under these demand settings we quantify the effect of a temporal heterogeneous variance on inventory performance for a system controlled via an order up to level policy we show that the effect of temporal heteroscedasticity on the forecasting accuracy can be additively decomposed from the total forecasting error variance the decomposition is used to derive the absolute and relative cost deviations when the temporal heteroscedasticity is ignored the relationship of these cost deviations to demand autocorrelation and replenishment leadtime is investigated computational results show that ignoring temporal heteroscedasticity can increase firm s inventory costs by as much as 30 when demand autocorrelation is highly positive

a time series framework for supply chain inventory management we consider a supply chain in which the underlying demand process can be described in a linear state space form inventory is managed at various points of the chain members based on local information that each member observes and continuously updates the key feature of our model is that it takes into account the ability of the members to observe subsets of the underlying state vector and adopt their forecasting and replenishment policies accordingly this enables us to model situations in which the members are privy to certain explanatory variables of the demand with the latter possibly evolving according to a vector autoregressive time series for each member we identify an associated demand evolution model for which we propose an adaptive inventory replenishment policy that utilizes the kalman filter technique we then provide a simple methodology for assessing the benefits of various types of information sharing agreements between members of the supply chain we also discuss inventory positioning and cost performance assessment in the supply chain our performance metrics and inventory target levels are usually presented in matrix forms allowing them to accommodate a relatively large spectrum of linear demand models and making them simple to implement several illustrations for possible applications of our models are provided

static and dynamic effects of health policy evidence from the vaccine industry public policies designed to increase utilization of existing technologies may also affect incentives to develop new technologies this paper investigates this phenomenon by examining policies designed to increase usage of preexisting vaccines i find that these policies were associated with a 2 5 fold increase in clinical trials for new vaccines for several diseases the induced innovation is socially wasteful though small in magnitude in one case however the dynamic social welfare benefits from induced innovation exceed the policies static benefits from increasing vaccination with existing technology these findings underscore the importance of including technological progress in economic analysis of public policy

disease and development the effect of life expectancy on economic growth we exploit the major international health improvements from the 1940s to estimate the effect of life expectancy on economic performance we construct predicted mortality using preintervention mortality rates from various diseases and dates of global interventions predicted mortality has a large impact on changes in life expectancy starting in 1940 but no effect before 1940 using predicted mortality as an instrument we find that a 1 percent increase in life expectancy leads to a 1 7 2 percent increase in population life expectancy has a much smaller effect on total gdp however consequently there is no evidence that the large increase in life expectancy raised income per capita

the impact of pricing policy on sales variability in a supermarket retail context abstract the bullwhip effect is recognized to be a significant cost driver in supply chains one of the measures proposed frequently to counter bullwhip effect is price stability through everyday low pricing edlp however this study suggests that with an auto regressive ar1 demand process the use of constant instead of dynamic pricing may result in lower profitability and higher demand volatility an optimal price and stocking level policy is developed with normally distributed demand in this study and the model is tested using parameters from a supermarket scanner data set to determine the impact of two pricing policies the hypothesis that low prior period demand leads to discounted pricing is also tested and partially supported

disease and development revisited acemoglu and johnson 2007 present evidence that improvements in population health do not promote economic growth we show that their result depends critically on the assumption that initial health has no causal effect on subsequent economic growth we argue that such an effect is likely primarily because childhood health affects adult productivity in our augmented model which includes initial health the instrumental variable proposed by acemoglu and johnson has no significant predictive power for improvements in health and does not identify the effect of contemporaneous improvements in health on economic growth this abstract was borrowed from another version of this item

your money or your life green growth policies and welfare in 2050 this paper proposes a simple index of economic progress that weighs in the monetary cost induced by climate change mitigation policies as well as the health benefits arising from the reduction in local air pollution the shadow price of pollution is calculated indirectly through its impact on life expectancy taking into account the health benefits of mitigation policies significantly reduces their monetary cost in china and india as well as in countries with large fossil based energy producing sectors australia canada and the united states

life expectancy and human capital evidence from the international epidemiological transition exploiting preintervention variation in mortality from various infectious diseases together with the time variation arising from medical breakthroughs in the late 1940s and the 1950s this study examines how a large positive shock to life expectancy influenced the formation of human capital within countries during the second half of the 20th century the results establish that the rise in life expectancy was behind a significant part of the increase in human capital over this period according to the baseline estimate for one additional year of life expectancy years of schooling increase by 0 17 year moreover the evidence suggests that declines in pneumonia mortality are the underlying cause of this finding indicating that improved childhood health increases human capital investments

market power screens willingness to pay what is the best way to reward innovation while prizes avoid deadweight loss intellectual property selects high social surplus projects optimal innovation policy thus trades off the ex ante screening benefit and the ex post distortion it solves a multidimensional screening problem in the private information held by the innovator research cost quality and market size of the innovation the appropriate degree of market power is never full monopoly pricing and is determined by measurable market characteristics the inequality and elasticity of innovation supply making the analysis open to empirical calibration the framework has applications beyond ip policy to the optimal pricing of platforms or the optimal procurement of public infrastructure

preventives versus treatments preventives are sold ex ante before disease status is realized while treatments are sold ex post even if the mean of the ex ante distribution of consumer values is the same as that ex post the shape of the distributions may differ generating a difference between the surplus each product can extract if for example consumers differ only in ex ante disease risk then a monopolist would have more difficulty extracting surplus with a preventive than with a treatment because treatment consumers having contracted the disease no longer differ in disease risk we show that the ratio of preventive to treatment producer surplus can be arbitrarily small in particular when the distribution of consumer values has a zipf shape and the disease is rare the firm s bias toward treatments can be reversed for example if the source of private information is disease severity learned ex post the difference between the producer surplus earned from the products can result in distorted rd the deadweight loss from this distortion can be as large as the entire producer surplus difference calibrations for hiv and heart attacks based on risk factors in the u s population suggest that the distribution of disease risk is sufficiently zipf similar to generate substantial differences between producer surplus from preventives and treatments empirically we find that proxies for the zipf similarity of the disease risk distribution are associated a significantly lower likelihood of vaccine development but not drug development jel codes o31 l11 i18 d42

endogenous information acquisition in supply chain management in this paper we analyze an endogenous determination of efforts put into information acquisition and its impact on supply chain management more specifically we consider a supplier who sells a product to a buyer during a single selling season prior to placing an order with the supplier the buyer has an option to acquire additional information about the demand by hiring experts who are capable of providing forecasts because a commission fee must be paid to each hired expert there exists a tradeoff between the cost and the value of the information and the buyer needs to determine how much information to acquire we derive the optimal information acquisition level in an integrated setting and compare it with that determined in a decentralized setting we also analyze several types of supply contracts to examine if they can coordinate the supply chain and allow an arbitrary division of system profit between the supplier and the buyer

the impacts of the full returns policy on a supply chain with information asymmetry abstract in contrast to the existing return policies literature assuming that information is symmetrical between the manufacturer and the retailer we study the full returns policy s impact on supply chains with information asymmetry we first study the case that the base level of the demand follows a discrete distribution with two states we find that the retailer benefits from the full returns policy in all circumstances while the manufacturer and the supply chain are better off under some conditions we then consider the situation in which the base level of the demand is a type of ar 1 process

how to measure the economic impact of vector borne diseases at country level vector borne diseases vbds are widespread in less developed countries and reemerging in developed ones available economic studies agree that vbds have significant effects on countries economic outcomes and affirm that a systematic evaluation of such effects is crucial for the efficient allocation of resources to health related priorities this paper provides a comparative assessment of available methodologies for measuring the economic impact of vbds at national level we review both macroeconometric and micro based approaches and examine advantages and disadvantages of current methods we conclude by suggesting possible areas for future research

durable goods monopoly with stochastic values i analyze a durable goods model that allows consumers values to vary over time the optimal mechanism for a monopolist is computed and compared to both the sales and leasing equilibria i show that sales may implement the optimal strategy and that the dominance of leasing over sales is not necessarily true this implication is consistent with the prevalence of simple sales contracts in many markets copyright 2001 by the rand corporation

health insurance as a two part pricing contract monopolies appear throughout health care we show that health insurance operates like a conventional two part pricing contract that allows monopolists to extract profits without inefficiently constraining quantity when insurers are free to offer a range of insurance contracts to different consumer types health insurance markets perfectly eliminate deadweight losses from upstream health care monopolies frictions limiting the sorting of different consumer types into different insurance contracts restore some of these upstream monopoly losses which manifest as higher rates of uninsurance rather than as restrictions in quantity utilized by insured consumers empirical analysis of pharmaceutical patent expiration supports the prediction that heavily insured markets experience little or no efficiency loss under monopoly while less insured markets exhibit behavior more consistent with the standard theory of monopoly

the rise in life expectancy and economic growth in the 20th century this research exploits conditional exogenous variation in mortality from the diffusion of modern medicine to study the effect of growth in life expectancy on the growth in gdp per capita the empirical analysis establishes that countries that obtained higher growth rates of life expectancy due to this shock to mortality in the mid twentieth century experienced lower growth rates of gdp per capita in the second half of the twentieth century in addition a negative relationship between initial level of life expectancy and the subsequent growth rate of gdp per capita is found

on delineating supply chain cash flow under collectionrisk abstract the credit terms for accounts receivable ar offered by sellers to buyers not only create a time lag between supply chain physical flow and cash flow but also increase the collection risk contributed by late collection and default previous studies describing the relationship between the two major supply chain flows did not consider the collection risk which poses a serious challenge to companies with limited cash resources when seeking growth opportunities in sales this study first delineates the relationship between the two flows during a growth period without imposing any constraints a stochastic optimization model is then developed to observe the managerial implications of cash flow risk under tight cash constraints

the effect of health improvements due to tobacco control on earnings in the united states there is minimal evidence causally estimating the relationship between tobacco tax policy population health and earnings this article uses state tobacco taxes as an instrument for life expectancy to estimate the effect on earnings per capita in a panel of almost 3000 counties in the united states over the period 1970 to 2000 in the first stage of the model we find that a one dollar increase in state tobacco taxes significantly increases life expectancy between 1 9 and 2 1 despite showing that tobacco tax is correlated with higher life expectancy and that theoretically improvements in health from reductions in smoking should lead to increased earnings we find an insignificant impact of the induced gains in life expectancy from tobacco policy on county level earnings per capita over the period 1970 to 2000 the lack of significance is explained through local average treatment effects and the smaller economic impact of certain policies that impact health later in life these results provide further

health care is an individual necessity and a national luxury applying multilevel decision models to the analysis of health care expenditures health care is neither a necessity or a luxury it is both since the income elasticity varies with the level of analysis with insurance individual income elasticities are typically near zero while national health expenditure elasticities are commonly greater than 1 0 the debate over whether health care is or is not a luxury good arises primarily from the failure to specify levels of analysis clearly so as to distinguish variation within groups from variation between groups apparently contradictory empirical results are shown to be consistent with a simple nested multilevel model of health care spending

the lazarus drug the impact of antiretroviral therapy on economic growth abstract does better population health lead to growth in per capita income theory is ambiguous and empirical evidence is very limited in 2001 a steep fall in antiretroviral arv drug prices triggered rapid and massive expansion of arv therapy coverage in lower income countries exploiting the sharp resultant changes in population health i show that arv therapy coverage expansion led to growth in gdp per capita the positive effects on growth most likely persist for around four years arv therapy coverage expansion could explain around a third of the sub saharan african growth miracle

internal supply chain coordination in the electric utility industry abstract electric utilities have a well established vertical internal and external supply chain theoretically information sharing involving production inventory and other policy variables between chain entities can improve supply chain performance such sharing relies on a systematic determination of the optimal policy variables for the chain this paper presents an analysis of the electric utility s decision problem based on an optimal control model in a competitive market environment optimal production and inventory policies are developed for a centralized supply chain under full information sharing the model and policies are tested with electric utility industry data and performance implications are discussed for electric utility managers and public regulators

disease and development evidence from the american south hookworm and malaria parasites that remain a significant public health threat in the tropical belt today were endemic in the american south as late as the first half of the twentieth century i discuss how the successful eradication of malaria and hookworm in the american south affected human capital accumulation i find that areas that had higher levels of malaria or hookworm infection prior to eradication experienced greater increases in school attendance and literacy afterwards moreover i find that adults earned substantially more if they were not exposed to these diseases as children the estimates are large relative to the subsequent convergence between the north and south in the united states but small compared to the cross country distribution of income nevertheless the results indicate potentially large benefits of public health interventions in developing countries jel i12 j24 o10 h43

the determinants of mortality mortality rates have fallen dramatically over time starting in a few countries in the 18th century and continuing to fall today in just the past century life expectancy has increased by over 30 years at the same time mortality rates remain much higher in poor countries with a difference in life expectancy between rich and poor countries of also about 30 years this difference persists despite the remarkable progress in health improvement in the last half century at least until the hiv aids pandemic in both the time series and the cross section data there is a strong correlation between income per capita and mortality rates a correlation that also exists within countries where richer better educated people live longer we review the determinants of these patterns over history over countries and across groups within countries while there is no consensus about the causal mechanisms we tentatively identify the application of scientific advance and technical progress some of which is induced by income and facilitated by education as the ultimate determinant of health such an explanation allows a consistent interpretation of the historical cross country and within country evidence we downplay direct causal mechanisms running from income to health

appropriation and efficiency a revision of the first theorem of welfare economics the first theorem of welfare economics rests on the assumption that individuals have neither price making nor market making capacities we offer a revision in which individuals have such capacities the revision emphasizes two keys for market efficiency i the need to align private rewards with social contributions called full appropriation and ii the need for an assumption to counter the possibility of coordination failures in the choice of produced commodities called noncomplementarity we also emphasize that information about prices of unmarketed commodities involves decentralized knowledge available only to product innovators and that pecuniary extemalities are important potential sources of market failure jel d51 d60 d62

bayes solution to dynamic inventory models under unknown demand distribution this paper considers the periodic review inventory problem for which one or more parameters of the demand distribution are unknown with a known prior distribution chosen from the natural conjugate

the value of public information in monopoly the logic of the linkage principle of milgrom and weber 1982 extends to price discrimination a non linear pricing monopolist who sells to a single buyer always prefers to commit to publicly reveal information a liated to the valuation of the buyer

disease and development a reply to bloom canning and fink bloom canning and fink 2014 argue that the results in acemoglu and johnson 2006 2007 are not robust because initial level of life expectancy in 1940 should be included in our regressions of changes in gdp per capita on changes in life expectancy we assess their claims controlling for potential lagged effects of initial life expectancy using data from 1900 employing a nonlinear estimator suggested by their framework and using information from microeconomic estimates on the effects of improving health there is no evidence for a positive effect of life expectancy on gdp per capita in this important historical episode this abstract was borrowed from another version of this item

bounding the relative profitability of price discrimination we derive bounds on the ratio of a monopolist s profit from third degree price discrimination to that from uniform pricing if the monopolist serves n independent markets demand is continuous and the cost function is superadditive then the profit ratio is bounded by n a linear demand example is provided coming arbitrarily close to this bound we provide examples showing the profit ratio can be unboundedly large when marginal cost is decreasing demand is discontinuous or fixed cost is positive if the monopolist has access to certain demand rationing strategies under uniform pricing we can bound the profit ratio even for discontinuous demand functions and multiproduct cost functions

perfect competition and the creativity of the market from the perspective of the walrasian general equilibrium model entrepreneurial and opportunistic behavior seems foreign can the model be refashioned so that it can accommodate such behavior many would say no but we argue the contrary indeed we present a reformulation of the model that serves as a gateway to rather than a detour from such contemporary issues as innovation and incentives the trick is to reexamine what perfect competition means starting with an historical summary of general equilibrium we sketch an image of the perfect competitor as an active market opportunist seeking out profit potentials wherever he can

the bullwhip effect in supply chain networks this paper analyzes the propagation and amplification of order fluctuations i e the bullwhip effect in supply chain networks operated with linear and time invariant inventory management policies the supply chain network is allowed to include multiple customers e g markets any network structure with or without sharing information the paper characterizes the stream of orders placed by any supplier for any stationary customer demand processes and gives exact formulas for the variance of the orders placed and the amplification of order fluctuations the paper also derives robust analytical conditions based only on inventory management policies to predict the presence of the bullwhip effect for any network structure any inventory replenishment policies and arbitrary customer demand processes numerical examples show that the analytical results accurately quantify the bullwhip effect managerial insights are drawn from the analysis the methodology presented in this paper generalizes those in previous studies for serial supply chains

tax subsidy policies toward vector borne infectious diseases abstract vector borne diseases especially rife in poor countries pose sectoral tax subsidy issues preventions and therapies mitigate these diseases in a numerical optimization model combining dynamic epidemiology and economics the medical distinction between prevention and therapy does not distinguish economic properties of preventions and therapies some interventions increase and others decrease moving to the steady state depending on the utility function the targeting of interventions and the disease process interventions display negative own price but indeterminate cross price effects juxtaposing the social planner s with decentralized choices quantifies externalities and shows how subsidies implement the first best one prevention and the therapy are equally subsidized

impact of product pricing and timing of investment decisions on supply chain co opetition abstract in supply chain co opetition firms simultaneously compete and co operate in order to maximize their profits we consider the nature of co opetition between two firms the product supplier invests in the technology to improve quality and the purchasing firm buyer invests in selling effort to develop the market for the product before uncertainty in demand is resolved we consider three different decision making structures and discuss the optimal configuration from each firm s perspective in case 1 the supplier invests in product quality and sets the wholesale price for the product the buyer then exerts selling effort to develop the market and following demand potential realization sets the resale price in case 2 the supplier invests in product quality followed by the buyer s investment in selling effort then after demand potential is observed the supplier sets the wholesale price and the buyer sets the resale price finally in case 3 both firms simultaneously invest in product quality and selling effort respectively subsequently observing the demand potential the supplier sets the wholesale price and the buyer sets the resale price we compare all configuration options from both the perspective of the supplier and the buyer and show that the level of investment by the firms depends on the nature of competition between them and the level of uncertainty in demand our analysis reveals that although configuration 1 results in the highest profits for the integrated channel there is no clear dominating preference on system configuration from the perspective of both parties the incentives of the co opetition partners and the investment levels are mainly governed by the cost structure and the level of uncertainty in demand we examine and discuss the relation between system parameters and the incentives in desiging the supply contract structure

information transmission and the bullwhip effect an empirical investigation the bullwhip effect is the amplification of demand variability along a supply chain a company bullwhips if it purchases from suppliers more variably than it sells to customers such bullwhips amplifications of demand variability can lead to mismatches between demand and production and hence to lower supply chain efficiency we investigate the bullwhip effect in a sample of 4 689 public u s companies over 1974 2008 overall about two thirds of firms bullwhip the sample s mean and median bullwhips both significantly positive respectively measure 15 8 and 6 7 of total demand variability put another way the mean quarterly standard deviation of upstream orders exceeds that of demand by 20 million we decompose the bullwhip by information transmission lead time estimating the bullwhip s information lead time components with a two stage estimator we find that demand signals firms observe with more than three quarters notice drive 30 of the bullwhip and those firms observe with less than one quarter s notice drive 51 from 1974 1994 to 1995 2008 our sample s mean bullwhip dropped by a third this paper was accepted by christian terwiesch operations management

inventory dynamics in process industries an empirical investigation process industry firms have thrived in recent decades but changes in the markets are currently putting both growth and profitability at risk in this context inventory management is increasingly viewed as an essential lever for creating a sustainable competitive advantage despite this many firms struggle to implement best practices because of industry specific constraints this research explores how seven fundamental characteristics of process industries drive inventory performance we empirically investigate four process industries and four peer industries using financial accounting credit rating stock market and trading data and implement a seemingly unrelated regression sur equations model our results show that capital intensity capital costs transportation costs delivery time price volatility demand uncertainty and gross margin directly affect a company s degree of freedom in terms of inventory management and illustrate that inventory management in process industries follows different dynamics this study enhances the understanding of inventory drivers and gives practitioners a tool to guide future improvement efforts

retailer policy uncertainty reduction and supply chain performance abstract we investigate how the retailer s inventory policy affects the total cost of a serial supply chain when the retailer uses the locally optimal s s policy there is randomness in order time and order quantity to the supplier whereas the supplier sees randomness only in order quantity for the suboptimal r t policy and only in order time for another suboptimal q r policy using an extensive computational study we find that the suboptimal policies perform better from the total supply chain perspective the benefit of policy changes is magnified when the retailer costs are low when the supplier costs are high and when there is information sharing

externalities and compulsary vaccinations abstract this paper challenges the conventional wisdom that because of the free rider problem a case can be made for compulsary vaccination against infectious disease for a very general class of models requiring that all individuals be vaccinated is strictly dominated by free choice the market allocation is not optimum and in the full information optimum some individuals would be compelled to be vaccinated this allocation can be achieved by taxes and subsidies however the government can exploit the revelation properties of vaccination and achieve an even better allocation than the full information optimum

stalking information bayesian inventory management with unobserved lost sales retailers are frequently uncertain about the underlying demand distribution of a new product when taking the empirical bayesian approach of scarf 1959 they simultaneously stock the product over time and learn about the distribution assuming that unmet demand is lost and unobserved this learning must be based on observing sales rather than demand which differs from sales in the event of a stockout using the framework and results of braden and freimer 1991 the cumulative learning about the underlying demand distribution is captured by two parameters a scale parameter that reflects the predicted size of the underlying market and a shape parameter that indicates both the size of the market and the precision with which the underlying distribution is known an important simplification result of scarf 1960 and azoury 1985 which allows the scale parameter to be removed from the optimization is shown to extend to this setting we present examples that reveal two interesting phenomena 1 a retailer may hope that compared to stocking out realized demand will be strictly less than the stock level even though stocking out would signal a stochastically larger demand distribution and 2 it can be optimal to drop a product after a period of successful sales we also present specific conditions under which the following results hold 1 investment in excess stocks to enhance learning will occur in every dynamic problem and 2 a product is never dropped after a period of poor sales the model is extended to multiple independent markets whose distributions depend proportionately on a single unknown parameter we argue that smaller markets should be given better service as an effective means of acquiring information

reliability evaluation and adjustment of supply chain network design with demand fluctuations this study focuses on supply chain network design problems by considering economies of scale and demand fluctuations a reliability evaluation method is developed to evaluate the performance of plants under demand fluctuations in addition two mathematical programming models are developed to determine the optimal adjustment decisions regarding production reallocation among plants under different fluctuating demands the judgments to adjust or to do nothing are investigated by comparing the results if the adjustment is made or not made results show that making adjustments benefits the manufacturers by reducing total production cost and avoiding revenue loss which outweighs the extra costs especially for high value added products results also suggest that the manufacturer should ignore a short period abnormal state since the benefits to respond to it might not compensate the high allocation costs the results of this study provide a reference for the manufacturer in their decision making process of network planning with demand fluctuations when they have to cope with benefits and costs during abnormal states

myopic policies for some inventory models with uncertain demand distributions the majority of papers on stochastic inventory theory make the assumption that the distribution of consumer demand in each time period is known with certainty while this assumption is unsupported in many applied contexts it is conventionally held that more realistic models are more difficult to solve and will not yield simple operational policies this paper shows that a simple inventory policy based upon a critical fractile can be optimal or near optimal in some inventory models with parameter adaptive demand processes in these some parameter of the demand distribution is not known with certainty and estimates of the parameter are updated in a statistical fashion as demand is observed through time examples include exponentially smoothed forecasts and bayesian updating of parameter estimates bounds on the value loss relative to optimal cost when using the critical fractile policy can be calculated directly from the problem data some numerical examples illustrate the technique

a note on price discount based on early order commitment in a single manufacturer multiple retailer supply chain abstract early order commitment eoc is a strategy for supply chain coordination wherein the retailer commits to purchasing from a manufacturer a fixed order quantity a few periods in advance of the regular delivery lead time in this paper we formulate and analyze the eoc strategy for a decentralized two level supply chain consisting of a single manufacturer and multiple retailers who face external demands that follow an autocorrelated ar 1 process over time we characterize the special structure of the optimal solutions for the retailers eoc periods to minimize the total supply chain cost and discuss the impact of demand parameters and cost parameters we then develop and compare three solution approaches to solving the optimal solution using this optimal cost as the benchmark we investigate the effectiveness of using the wholesale price discount scheme for the manufacturer to coordinate this decentralized system we give numerical examples to show the benefits of eoc to the whole supply chain examine the efficiency of the discount scheme in general situation and provide the special conditions when the full coordination is achieved

characterization of the bullwhip effect in linear time invariant supply chains some formulae and tests the authors analyze the bullwhip effect in multistage decentralized supply chains operated with linear and time invariant inventory management policies the focus is on robustness the supply chain is modeled as a single input single output control system driven by arbitrary customer demands the authors derive robust analytical conditions to predict the presence of the bullwhip effect and bound its magnitude based only on the way inventories are managed these results hold independently of the customer demand the authors also characterize the stream of orders placed at any stage of the chain when the customer demand process is known and ergodic and give an exact formula for the variance of the orders placed this formula generalizes existing results by broadening the class of inventory replenishment policies and customer demand processes to which it applies the authors also show that the bullwhip effect can be mitigated by introducing commitments for future orders into the ordering policies

behavioral causes of the bullwhip effect and the observed value of inventory information the tendency of orders to increase in variability as one moves up a supply chain is commonly known as the bullwhip effect we study this phenomenon from a behavioral perspective in the context of a simple serial supply chain subject to information lags and stochastic demand we conduct two experiments on two different sets of participants in the first we find the bullwhip effect still exists when normal operational causes e g batching price fluctuations demand estimation etc are removed the persistence of the bullwhip effect is explained to some extent by evidence that decision makers consistently underweight the supply line when making order decisions in the second experiment we find that the bullwhip and the underlying tendency of underweighting remains when information on inventory levels is shared however we observe that inventory information helps somewhat to alleviate the bullwhip effect by helping upstream chain members better anticipate and prepare for fluctuations in inventory needs downstream these experimental results support the theoretically suggested notion that upstream chain members stand to gain the most from information sharing initiatives

the induced innovation hypothesis and energy saving technological change we develop a methodology for testing hicks s induced innovation hypothesis by estimating a product characteristics model of energy using consumer durables augmenting the hypothesis to allow for the ine uence of government regulations for the products we explored the evidence suggests that i the rate of overall innovation was independent of energy prices and regulations ii the direction of innovation was responsive to energy price changes for some products but not for others iii energy price changes induced changes in the subset of technically feasible models that were offered for sale iv this responsiveness increased substantially during the period after energy efficiency product labeling was required and v nonetheless a sizable portion of efficiency improvements were autonomous

the risk of second tier supplier failures in serial supply chains implications for order policies and distributor autonomy abstract as organizations decrease inventory the potential impact of a supply disruption increases however due to supply chain structural changes the likelihood of a disruption may be less additionally independent supply chain actors may react to policy changes changing supply chain configurations and perhaps reducing loss magnitudes if risk is a product of likelihood and magnitude does higher inventory reduce an organization s supply related risk this paper examines the supply risk issue within the context of a second tier supply failure and is grounded in inventory and resource dependency theories by evaluating risk assessment in a simulation environment exploratory findings suggest that increased inventory in a tiered supply chain can sometimes increase supply risk rather than decrease it managerial insights into the effects of supply chain stability and coordination are provided by taking a systems perspective of supply risk management organizations will be better able to manage supply risk concerns

customer order information leadtimes and inventories we have an inventory to manage the scenario is standard in all respects save one instead of arriving unannounced customers provide advance warning of their demands how should we use this information and what is its effect on system performance the answers turn out to be strikingly simple there are very simple policies which perform effectively in some cases optimally also such demand leadtimes improve performance in precisely the same way that replenishment leadtimes degrade it

the effects of information transparency on suppliers manufacturers and consumers in online markets this paper looks into the effects of information transparency on market participants in an online trading environment we study these effects in business to business electronic markets with firms competing in both upstream and downstream industries the prior literature generally assumes that either the downstream firm buyer or the upstream firm seller is a monopoly it is not clear whether information transparency would still create value if both buyers and sellers face oligopolistic competition where the benefits of information transparency could be competed away to answer this question we first develop a simple two echelon e market model and then extend the model to more general settings we find that information transparency can create value for the overall e market yet it affects buyers and sellers very differently one side will be hurt depending on the competition mode cournot or bertrand in the downstream this suggests that a manufacturer owned a supplier owned and a neutral e market will have different preferences for information transparency finally we find that information transparency can hurt consumers when the downstream industry engages in bertrand competition this is a surprising result given the expectation that online markets create substantial value for consumers

risk sharing in supply chains using order bands analytical results and managerial insights abstract this work generalizes and extends a number of basic production inventory models we study a periodic review non stationary markovian production inventory model with stochastic demand and holding and penalty costs all state dependent where goods can be procured from up to two suppliers each supplier quotes a state dependent minimum order quantity moq order capacity c and unit price we concentrate on a base stock policy that is defined by a vector of numbers one for each lead time indexed by the states of the markov chain in certain cases our policy is optimal for the general case we show that there is no simple optimal policy we use infinitesimal perturbation analysis to compute inventory levels within this class for an application motivated by international trade for this application we find that the imposition of minimum and or maximum order quantities provides an effective mechanism for risk sharing the customer guarantees the supplier a minimum order every period at an increased unit price and in exchange the supplier grants an increase in capacity this can more effectively match supply with demand making the entire supply chain more profitable

information sharing and order variability control under a generalized demand model the value of information sharing and how it could address the bullwhip effect have been the subject of studies in the literature most of these studies used different forms of demand models assuming that no order smoothing was used by the retailer and that the supplier has full knowledge of the retailer s demand model and order policy in this paper we contribute to the literature by starting with a most general demand model coupled with a smoothing policy for order variability control in addition we do not require that the supplier has full knowledge of the retailer s demand model and order policy but instead let the retailer share its projected future orders and freely revise them as the retailer sees fit under such a setting we first obtain a unifying formula for the magnitude of the bullwhip effect the formula indicates that it is the forecast correlation over the exposure period as a whole that determines the magnitude of the bullwhip effect we then quantify the value of information sharing and generalize the existing results in the literature finally we explore the optimal smoothing parameters that could benefit the total supply chain the resulting optimal policy resembles the postponement strategy we find that information sharing together with order postponement improves the supply chain performance even though the order variability may amplify in some cases

integrated production distribution planning in supply chains an invited review ss selc suk ereng uc s n c simpson asoo j vakharia c a department of decision and information sciences college of business administration university of florida gainesville fl 32611 7169 usa b department of management science and systems school of management university at bu alo bu alo ny 14260 4000 usa c department of decision and information sciences college of business administration university of florida 343 bus p o box 117169 gainesville fl 32611 7169 usa

value of information in capacitated supply chains we incorporate information flow between a supplier and a retailer in a two echelon model that captures the capacitated setting of a typical supply chain we consider three situations 1 a traditional model where there is no information to the supplier prior to a demand to him except for past data 2 the supplier knows the s s policy used by the retailer as well as the end item demand distribution and 3 the supplier has full information about the state of the retailer order up to policies continue to be optimal for models with information flow for the finite horizon the infinite horizon discounted and the infinite horizon average cost cases study of these three models enables us to understand the relationships between capacity inventory and information at the supplier level as well as how they are affected by the retailer s s s values and end item demand distribution we estimate the savings at the supplier due to information flow and study when information is most beneficial

inventory control in a fluctuating demand environment we present an inventory model where the demand rate varies with an underlying state of the world variable this variable can represent economic fluctuations or stages in the product life cycle for example we derive some basic characteristics of optimal policies and develop algorithms for computing them in addition we show that certain monotonicity patterns in the problem data are reflected in the optimal policies

information design in the holdup problem we analyze a bilateral trade model where the buyer chooses the distribution of her valuation for the good the seller after observing the buyer s distribution but not the realized valuation makes a take it or leave it offer if distributions are costless the price and the payoffs of both the buyer and the seller are shown to be 1 e in the unique equilibrium outcome the buyer s equilibrium distribution generates a unit elastic demand and trade is ex post efficient these properties are shown to be preserved even when different distributions are differentially costly as long as the cost is monotone in the dispersion of the distribution

supplying information to facilitate price discrimination the authors examine the incentive of a seller to allow potential buyers to acquire private information about their tastes for the seller s product improved private information for buyers enables the seller to segment the market and charge higher prices to high value buyers however improved information can also provide rents to buyers in a variety of settings this tradeoff is optimally resolved at one of two extremes either buyers are supplied with the best available knowledge of their tastes or no information is supplied by the seller copyright 1994 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association

cause of death and development in the us abstract exploiting cross state variation in infectious causes of death along with time variation arising from medical innovations toward the middle of the twentieth century this study examines the consequences of a positive health shock in the us it establishes that states with higher levels of mortality from infectious causes prior to the onset of the era of big medicine experienced greater increases in life expectancy population and total gdp after its onset whereas per capita gdp remained largely unchanged together the evidence suggests that the rise in life expectancy had no significant effect on living standards in the us during the time period 1940 1980 these results are robust to controlling for initial health and initial economic conditions

using scheduled ordering to improve the performance of distribution supply chains we study a supply chain with one supplier and many retailers that face exogenous end customer demands the supplier and the retailers all try to minimize their own inventory related costs in contrast to the retailers newsvendor type ordering behavior under which retailers may place orders freely in every period we propose two scheduled ordering policies the scheduled balanced ordering policy sbop and the scheduled synchronized ordering policy ssop under both the sbop and ssop retailers are allowed to order freely only in one period of an ordering cycle and receive fixed shipments in other periods retailers take turns to order freely under the sbop while under the ssop all retailers order freely in the same period with the average supply chain cost per period as the performance measure we identify mathematical conditions under which scheduled ordering policies outperform the newsvendor type ordering through a large scale numerical study we find that scheduled ordering policies are most effective when i the supplier s holding and expediting costs are high and the retailer s backorder cost is small ii the end customer demand variance and correlation are high and iii the supplier s capacity is high in addition we observe that the behavior of the ssop often complements that of the sbop whereas the sbop is better than ssop when the supplier s capacity is low and when the end customer demand correlation level is high the ssop is better when the opposite conditions prevail

dynamic epidemiology and the market for vaccinations abstract the intent of this paper is to raise the question of how and when externalities can arise in the market for vaccinations static and dynamic models of such markets are developed and compared a special case in a continuous time dynamic framework is examined and is found to be efficient i e there is no externality this is in contrast to the results from the static formulation raising doubts about the suitability of a static approach these results indicate that the question of whether there are externalities in individual immunization decisions is more involved than is generally supposed

ordering and pricing decisions in a two echelon supply chain with asymmetric demand information abstract this article examines coordinated decisions in a decentralized supply chain that consists of one supplier and one retailer and faces random demand of a single product with a short life cycle we consider a setting where the retailer has accurate demand information while the supplier does not such a problem with asymmetric demand information can be viewed as an extension of the newsboy problem in which both the supplier and the retailer possess the same demand information combining the mechanism of sharing demand information and that of quantity discount and return policy enables us to develop three coordinated models in contrast with the basic and uncoordinated model we are able to show the ordinal relationship among the retailer s optimal order quantities in these four models under a general form of random demand and compare the supply chain profits and conduct sensitivity analysis analytically in four models under uniform random demand we also provide numerical results under normal random demand that bear a resemblance to those under uniform random demand

a stackelberg model of pricing of complementary goods under information asymmetry abstract we consider a duopoly market where two separate firms offer complementary goods in a leader follower type move each firm has private forecast information about the uncertain market demand and decides whether to share it with the other firm we show that information sharing would benefit the leader firm but hurt the follower firm as well as the total system if the follower firm shares information unconditionally we then devise a simple to implement information sharing scheme under which both firms and the total system are better off we also provide several interesting managerial insights and establish the robustness of the model in managing a supply chain through our analytical and simulation results

inventory management with asset based financing most of the traditional models in production and inventory control ignore the financial states of an organization and can lead to infeasible practices in real systems this paper is the first attempt to incorporate asset based financing into production decisions instead of setting a known exogenously determined budgetary constraint as most existing models suggest we model the available cash in each period as a function of assets and liabilities that may be updated periodically according to the dynamics of the production activities furthermore our models allow different interest rates on cash balance and outstanding loans which is an enhancement over most traditional models in that inventory financed by a loan may be more expensive than that by out of pocket cash we demonstrate the importance of joint consideration of production and financing decisions in a start up setting in which the ability to grow the firm is mainly constrained by its limited capital and dependence on bank financing we then explain the motivation for asset based financing by examining the decision making at a bank and a set of retailers in a newsvendor setting

on the simple economics of advertising marketing and product design we propose a framework for analyzing transformations of demand such transformations frequently stem from changes in the dispersion of consumers valuations which lead to rotations of the demand curve in many settings profits are a u shaped function of dispersion high dispersion is complemented by niche production and low dispersion is complemented by mass market supply we investigate numerous applications including product design advertising marketing and sales advice and the construction of quality differentiated product lines we also suggest a new taxonomy of advertising distinguishing between hype which shifts demand and real information which rotates demand

impact of information sharing and lead time on bullwhip effect and on hand inventory abstract this work analyzes a two echelon warehouse retailer serial supply chain to study the impact of information sharing is and lead time on bullwhip effect and on hand inventory the customer demand at the retailer is assumed to be an autoregressive ar 1 process both the echelons use a minimum mean squared error mmse model for forecasting lead time demand ltd and follow an adaptive base stock inventory policy to determine their respective order quantities for the cases of without is and inter as well as intra echelon is expressions for the bullwhip effect and on hand inventory for the warehouse are obtained considering deterministic lead time the results are compared with the previous research work and an easy analysis of the various bullwhip effect expressions under different scenarios is done to understand the impact of is on the bullwhip effect phenomenon it is shown that some part of bullwhip effect will always remain even after sharing both inter as well as intra echelon information further with the help of a numerical example it is shown that the lead time reduction is more beneficial in comparison to the sharing of information in terms of reduction in the bullwhip effect phenomenon

technical note impact of inventory on quota bonus contracts with rent sharing we study the impact of limited inventory on optimal sales force compensation contracts we adopt a principal agent framework characterized by limited liability and rent sharing with the agent a commonly invoked assumption in the inventory management literature is that the demand distribution satisfies the increasing failure rate ifr property under this assumption however past research has established that a quota bonus contract a widely adopted sales force compensation contract in the practice cannot sustain in equilibrium we show that because of demand censoring in the presence of limited inventory i e demand realizations higher than the inventory level are unobservable a quota bonus contract is the optimal equilibrium contract and it exists even for a demand distribution with the ifr property since most well known distributions satisfy the ifr property and inventory constraints are operative in many real world situations our results significantly extend the scope of the optimality of q

modelling imperfect advance demand information and analysis of optimal inventory policies we consider an inventory control problem where it is possible to collect some imperfect information on future demand we refer to such information as imperfect advance demand information adi which may occur in different forms of applications a simple example is a company that uses sales representatives to market its products in which case the collection of sales representatives information as to the number of customers interested in a product can generate an indication about the future sales of that product hence it constitutes imperfect adi other applications include internet retailing vendor managed inventory vmi applications and collaborative planning forecasting and replenishment cpfr environments we develop a model that incorporates imperfect adi with ordering decisions under our system settings we show that the optimal policy is of order up to type where the order level is a function of imperfect adi we also provide some characterizations of the optimal solution we develop an expression for the expected cost benefits of imperfect adi for the myopic problem our analytical and empirical findings reveal the conditions under which imperfect adi is more valuable

efficiency and surplus bounds in cournot competition we derive bounds on the ratios of deadweight loss and consumer surplus to producer surplus under cournot competition to do so we introduce a parameterization of the degree of curvature of market demand using the parallel concepts of concavity and convexity the more concave is demand the larger the share of producer surplus in overall surplus the smaller is consumer surplus relative to producer surplus and the lower the ratio of deadweight loss to producer surplus deadweight loss over total potential surplus is at rst increasing with demand concavity then eventually

the effect of information sharing on supply chain stability and the bullwhip effect this paper analyzes the bullwhip effect in multi stage supply chains operated with linear and time invariant inventory management policies and shared supply chain information such information includes past order sequences and inventory records at all supplier stages the paper characterizes the stream of orders placed at any stage of the chain when the customer demand process is known and ergodic and gives an exact formula for the variance of the orders placed the paper also derives robust analytical conditions based only on inventory management policies to predict the presence of the bullwhip effect and bound its magnitude these results hold independently of the customer demand the general framework proposed in this paper allows for any inventory replenishment policies any ways of sharing and utilizing information and any customer demand processes it is also shown as a special case that sharing customer demand information across the chain significantly reduces but does not completely eliminate the bullwhip effect

coordination mechanisms of supply chain systems supply chain management scm has become an important management paradigm as supply chain members are often separate and independent economic entities a key issue in scm is to develop mechanisms that can align their objectives and coordinate their activities so as to optimize system performance in this paper we provide a review of coordination mechanisms of supply chain systems in a framework that is based on supply chain decision structure and nature of demand this framework highlights the behavioral aspects and information need in the coordination of a supply chain the identification of these issues points out several directions of future research in this area

a capacitated production inventory model with periodic demand for a single product single stage capacitated production inventory model with stochastic periodic cyclic demand we find the optimal policy and characterize some of its properties we study the finite horizon the discounted infinite horizon and the infinite horizon average cases a simulation based optimization method is provided to compute the optimal parameters based on a numerical study several insights into the model are also provided

the effect of foreknowledge of demand in case of a restricted capacity the single stage single product case abstract one of the important aspects of supply chain management is the possibility to realize advance demand information deeper in the chain foreknowledge of demand is useful in the control of a production inventory system knowing the customer orders in advance makes it possible to anticipate properly it is an important condition to produce and deliver the right quantity of the right product just in time it reduces the need of safety stock and spare capacity and it helps to reduce the bullwhip effect through the chain but the question of the effectiveness of foreknowledge is not an easy one having foreknowledge of the customer orders does not remove the demand uncertainty completely and the effect of the advance demand information may be hampered by the restricted flexibility of the resources the subject of this paper is the influence of a restricted production capacity on the effect of advance demand information the single stage single product case is considered here the lost sales version as well as the backlogging version the main result is that for high utilization rates and small forecast horizon the inventory reduction due to foreknowledge is equal to 1 h r with h the forecast horizon and r the production speed connected with that is the result that for small forecast horizon it is allowed to aggregate the demand information over the forecast horizon this leads to a heuristic that appears to be close to optimal for the case with a larger forecast horizon

pass through in a concentrated industry empirical evidence and regulatory implications we estimate pass through with thirty years of data from a concentrated industry the empirical model accounts for oligopoly interactions yet facilitates estimation with aggregate price data robust statistical evidence supports that industry wide cost changes are more than completely transmitted downstream and that this industry pass through is largely unaected by competitive conditions the industry in question portland cement is a major focus of environmental and antitrust regulators we use our pass through estimates to i evaluate the welfare consequences of marketbased co2 regulation ii predict the magnitude and location of price eects due to a merger under review by antitrust authorities and iii corroborate the simulation based analysis of the epa regarding its impending regulation of local pollutants

vaccination and gdp growth rates exploring the links in a conditional convergence framework summary vaccination rates vary significantly across countries and the intensity of vaccination programs is a matter of public choice infrastructure limitations budget constraints and many other factors the link between better health and better economic performance is by now well established and many vaccines have been shown to generate significant roi in a classical cost benefit framework to our knowledge the longer term macroeconomic benefits of improved vaccination programs have not been estimated we modify the standard conditional convergence model to account for changes in vaccination rates across time and countries and use the modified model to estimate the macroeconomic gains from improved vaccination rates using the dtp vaccine as a proxy for vaccination programs generally we find evidence to suggest economically and statistically significant and sustained increases in the gdp growth rate associated with lagged increases in vaccination rates furthermore we find these effects increasing over time we find that investments of the sort made by the global alliance for vaccination and immunization gavi are linked to measurably higher dtp rates and we estimate the returns to such investments as at least 12 1 for countries on the threshold of graduating from gavi these results suggest that much is at stake reducing investment in vaccination could reverse both the public health improvements and tangible economic benefits associated with ongoing improvements in vaccination rates

population and conflict medical innovations during the 1940s quickly resulted in significant health improvements around the world countries with initially higher mortality from infectious diseases experienced larger increases in life expectancy population and subsequent social conflict this cross country result is robust across alternative measures of conflict and is not driven by differential trends between countries with varying baseline characteristics a similar effect is also present within mexico initial suitability conditions for malaria varied across municipalities and anti malaria campaigns had differential effects on population growth and social conflict both across countries and within mexico increased conflict over scarce resources predominates and this effect is more pronounced during times of economic hardship specifically in countries with a poor growth record and in drought stricken areas in mexico at least during this time period a larger increase in population made social conflict more likely

the effect of health on economic growth a production function approach abstract we estimate a production function model of aggregate economic growth including two variables that microeconomists have identified as fundamental components of human capital work experience and health our main result is that good health has a positive sizable and statistically significant effect on aggregate output even when we control for experience of the workforce we argue that the life expectancy effect in growth regressions appears to be a real labor productivity effect and is not the result of life expectancy acting as a proxy for worker experience

demand forecast sharing in a dual channel supply chain abstract we assess the benefits of sharing demand forecast information in a manufacturer retailer supply chain consisting of a traditional retail channel and a direct channel the demand is a linear function of price with a gaussian primary demand i e zero price market potential both the manufacturer and the retailer set their price based on their forecast of the primary demand in this setting we investigate the value of sharing demand forecasts we analyze the make to order scenario in which prices are set before and production takes place after the primary demand is known and the make to stock scenario in which production takes place and prices are set before the primary demand is known we also compare the supply chain performance with and without the direct channel under some assumptions production cost is zero and each demand function has the same slope of price we find that the direct channel has a negative impact on the retailer s performance and under some conditions the manufacturer and the whole supply chain are better off our research extends and complements prior research that has investigated only the inventory and replenishment related benefits of information sharing

the limits of price discrimination we analyze the welfare consequences of a monopolist having additional information about consumers tastes beyond the prior distribution the additional information can be used to charge dierent prices to dierent segments of the market i e carry out third degree price discrimination we show that the segmentation and pricing induced by the additional information can achieve every combi nation of consumer and producer surplus such that i consumer surplus is non negative ii producer surplus is at least as high as pro ts under the uniform monopoly price and iii total surplus does not exceed the e cient gains from trade as well as characterizing the welfare impact of price discrimination we examine the limits of how prices and quantities can change under price discrimination we also examine the limits of price discrimination in richer environments with quantity discrimination and limited ability to segment the market

accounting for the effect of health on economic growth i use microeconomic estimates of the effect of health on individual outcomes to construct macroeconomic estimates of the proximate effect of health on gdp per capita i employ a variety of methods to construct estimates of the return to health which i combine with cross country and historical data on height adult survival rates and age at menarche using my preferred estimate eliminating health differences among countries would reduce the variance of log gdp per worker by 9 9 percent and reduce the ratio of gdp per worker at the 90th percentile to gdp per worker at the loth percentile from 20 5 to 17 9 while this effect is economically significant it is also substantially smaller than estimates of the effect of health on economic growth that are derived from cross country regressions