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

medical expenditure risk and household portfolio choice medical expenses are an increasingly important contributor to household financial risk we examine the effect of medical expenditure risk on the willingness of medicare beneficiaries to hold risky assets using a discrete factor maximum likelihood method to address the endogeneity of insurance choices we find that having a moderately protective medigap or employer supplemental policy increases risky asset holding by 7 1 percentage points relative to those without supplemental coverage while participation in a highly protective medicare hmo increases risky asset holding by 13 0 percentage points our results highlight an important link between the availability of health insurance and financial behavior

diffusion and spillover of new technology a heterogeneous agent model for cassava in west africa understanding what determines the geographic spread of innovations can help guide the funding and implementation of research and extension programs our approach uses household survey data as model parameters to simulate behavior across the entire surveyed population and avoid the aggregation bias associated with representative farm models such a heterogeneous agent approach allows us to infer the distribution of a technology s impacts across one set of households and predict the potential for spreading to another set that shares similar characteristics with respect to natural resource endowments and farming systems we apply the technique to new cassava varieties in west africa finding a strongly poverty alleviating impact with substantial spillover potential from nigeria to neighboring countries

efficiency of research investments in the presence of international spillovers wheat research in developing countries expenditures on agricultural research in the public sector including the international agricultural research centers iarcs have stagnated and in some cases declined sharply in recent years this has focused attention on issues of efficiency of agricultural research systems especially the number size scope type and locations of their programs this paper examines the issue of research efficiency through a case study of wheat improvement research in developing countries the basic premise of this study is that the optimal level of research investment should be determined in a global model that incorporates direct research spill ins an analytical framework is developed to determine the threshold levels of crop production in a country or a region within a country needed to justify crop improvement research programs of different sizes in the presence of spill ins from abroad spill in coefficients are estimated from yield performance of varieties of different origins grown across a range of environments the model is then applied to analyze the efficiency of current investments in 69 wheat improvement research programs in 35 developing countries a major conclusion of the paper is that given the magnitude of potential spill ins from the international research system many wheat research programs could significantly increase the efficiency of resource use by reducing the size of their wheat research programs and focusing on the screening of varieties developed elsewhere 2000 elsevier science b v all rights reserved

two stage residual inclusion estimation addressing endogeneity in health econometric modeling the paper focuses on two estimation methods that have been widely used to address endogeneity in empirical research in health economics and health services research two stage predictor substitution 2sps and two stage residual inclusion 2sri 2sps is the rote extension to nonlinear models of the popular linear two stage least squares estimator the 2sri estimator is similar except that in the second stage regression the endogenous variables are not replaced by first stage predictors instead first stage residuals are included as additional regressors in a generic parametric framework we show that 2sri is consistent and 2sps is not results from a simulation study and an illustrative example also recommend against 2sps and favor 2sri our findings are important given that there are many prominent examples of the application of inconsistent 2sps in the recent literature this study can be used as a guide by future researchers in health economics who are confronted with endogeneity in their empirical work

software piracy a strategic analysis and policy instruments abstract we examine the government s role in restricting commercial piracy in a software market welfare maximization may or may not result in monitoring as the socially optimal outcome correspondingly either monopoly situation or market sharing between an original firm and a pirate are subgame perfect equilibria if it is profitable for a monopolist to prevent piracy by installing a protective device then not monitoring is the equilibrium we also discuss the effects of network externalities in addition to deriving the effects of changes in the reliability of the pirated software and network benefits on the policy variables the extent of piracy and the monopolist s incentive to prevent piracy

optimal strategic pricing of reproducible consumer products this paper investigates the strategic pricing of consumer durable products which can be acquired through either purchase or reproduction e g computer software as copy piracy results in an opportunity loss its adverse effect on profits needs to be incorporated in strategic decisions such as pricing using a dual diffusion model which parsimoniously describes sales and copying and employing control theory methodology optimal price trajectories are derived for the period of monopoly the results indicate that a in absence of any protection skimming pricing strategies are generally optimal and b copy protection is warranted only when sales diffuse much faster than copying and the protection technology does not significantly raise the marginal production cost

the effects of increased copyright protection an analytic approach previous authors who have considered partially nonexcludable goods have claimed that an increase in copyright protection will have the following two effects on social welfare first it will decrease the social welfare loss due to underproduction second it will increase the social welfare loss due to underutilization in this paper we investigate these claims in a formal setting by analyzing a model in which consumers vary only in terms of their costs of obtaining a reproduction our analysis provides partial support to the first claim of these previous authors while giving little or no support to the second claim

uncertain medical expenses and precautionary saving near the end of the life cycle this paper introduces a dynamic structural model of household consumption decisions in which elderly families consider the effects of uncertain future medical expenses when deciding current levels of consumption the model with uncertain medical expenses implies a potentially important role for precautionary saving incentives to explain slow rates of dissaving among elderly americans during retirement rather than just simulating the stochastic dynamic model preference parameters are estimated using panel data on health wealth and expenditures for retired families the health uncertainty model predicts consumption levels closer to observed expenditures than a life cycle model with uncertain longevity however elderly families typically dissave their financial assets more slowly than even the baseline health uncertainty model predicts is optimal

the effect of piracy on the market penetration of subscription software software piracy is not necessarily harmful to a software firm seeking to launch a new product when strategically managed through the use of price and protection measures piracy establishes the initial adopters of the software who in turn influence other users to buy the product we examine the role of piracy in affecting the adoption of subscription software products we present an individual level model in an adaptive population setting intended to determine the price protection mix that maximizes the discounted profit stream over the life of the software an extension for nonsubscription software is also discussed

learning by doing and learning from others human capital and technical change in agriculture household level panel data from a nationally representative sample of rural indian households describing the adoption and profitability of high yielding seed varieties hyvs associated with the green revolution are used to test the implications of a model incorporating learning by doing and learning spillovers the estimates indicate that i imperfect knowledge about the management of the new seeds was a significant barrier to adoption ii this barrier diminished as farmer experience with the new technologies increased iii own experience and neighbors experience with hyvs significantly increased hyv profitability and iv farmers do not fully incorporate the village returns to learning in making adoption decisions

does medicare save lives health insurance characteristics shift at age 65 as most people become eligible for medicare we measure the impacts of these changes on patients who are admitted to hospitals through emergency departments for conditions with similar admission rates on weekdays and weekends the age profiles of admissions and comorbidities for these patients are smooth at age 65 suggesting that the severity of illness is similar on either side of the medicare threshold in contrast the number of procedures performed in hospitals and total list charges exhibit small but statistically significant discontinuities implying that patients over 65 receive more services we estimate a nearly 1 percentage point drop in 7 day mortality for patients at age 65 equivalent to a 20 reduction in deaths for this severely ill patient group the mortality gap persists for at least 9 months after admission

demand for medical care by the elderly a finite mixture approach summary in this article we develop a finite mixture negative binomial count model that accommodates unobserved heterogeneity in an intuitive and analytically tractable manner this model the standard negative binomial model and its hurdle extension are estimated for six measures of medical care demand by the elderly using a sample from the 1987 national medical expenditure survey the finite mixture model is preferred overall by statistical model selection criteria two points of support adequately describe the distribution of the unobserved heterogeneity suggesting two latent populations the healthy and the ill whose fitted distributions diaer substantially from each other 1997 by john wiley sons ltd

exploring strategic priorities for regional agricultural r d investments in east and central africa the 11 countries of east and central africa have diverse but overlapping agroclimatic conditions and could potentially benefit from spillovers of agricultural technology across country borders this article uses high resolution spatial data on actual and potential yields for 15 major products across 12 development domains to estimate the total benefits available from the spread of new agricultural technologies around the region market responses and welfare gains are estimated using the dynamic research evaluation for management model taking account of current and future projections of local and international demand results suggest which crops countries and agroclimatic regions offer the largest total benefits downloadable data and program files permit different assumptions and additional information to be considered in the ongoing process of strategic priority setting

copying and indirect appropriability photocopying of journals creators and owners of intellectual properties are alarmed by the growth of technologies that ease the tasks of copying these properties this paper however shows that the unauthorized copying of intellectual properties need not be harmful and actually may be beneficial the empirical impact of photocopying on publishers of journals is examined in an attempt to discover if publishers can indirectly appropriate revenues from users who are not original purchasers the evidence indicates that publishers can indirectly appropriate revenues from users who do not directly purchase journals and that photocopying has not harmed journal publishers 18 references 1 table

the gains from research into tradable commodities this paper develops a model for assessing the aggregate level and distribution of the benefits of reseach into tradable commodities it estimates gains to australia and to the rest of the world from research into the wool and wheat industries

impacts of price and productivity changes on banana growing households in uganda this article compares the effects of changing market prices and farm productivity on the welfare of banana growing households in the ntungamo district of uganda a heterogeneous agent model is applied via a series of mathematical optimization problems to simulate production and consumption responses of 70 farm households surveyed in 2006 results show that a given increase in productivity has a greater impact on poverty alleviation than that same increase in market prices despite the effects of productivity gains being comparable across different types of household groups price improvements primarily benefit the incomes of households who are involved in rural producer organizations who are located closer to markets and who sell at the market

optimal pricing for information goods with piracy and saturation effect we analyze the pricing decision of a firm selling a product for which there is a significant and continuous saturation effect over time and that can be pirated assuming that the firm uses a skimming strategy we solve three profit maximization models given demand that is linearly decreasing in price few prices can be used over the life of the product the effects of both piracy and saturation are combined in the first model in the second model the firm can invest in technology or copyright enforcement to reduce piracy the third model describes the case in which piracy leads to increased awareness of the product and increased demand numerical sensitivity analysis and examples are used to illustrate the results the results indicate that under strong piracy and saturation effects a skimming strategy is suboptimal

what did medicare do the initial impact of medicare on mortality and out of pocket medical spending abstract we study the impact of the introduction of one of the major pillars of the social insurance system in the united states the introduction of medicare in 1965 our results suggest that in its first 10 years the establishment of universal health insurance for the elderly had no discernible impact on elderly mortality however we find a substantial reduction in the elderly s exposure to out of pocket medical expenditure risk specifically we estimate that the introduction of medicare was associated with a 40 decline in out of pocket spending for the top quartile of the out of pocket spending distribution a stylized expected utility framework suggests that the welfare gains from such reductions in risk exposure alone may be sufficient to cover almost two fifths of the costs of medicare these findings underscore the importance of considering the direct insurance benefits from public health insurance programs in addition to any indirect benefits from an effect on health

chapter 11 pricing models in marketing publisher summary this chapter brings together a set of diverse efforts in the recent literature on the modeling of price decisions and related questions in marketing there has been an impressive growth in the array of topics investigated in the literature various trends in the development of pricing models are evident from the foregoing review first one trend has been to develop theoretical models to describe observed pricing strategies in the marketplace and to derive conditions under which certain strategies are optimal this trend is clearly evident when one considers the area of dynamic pricing models another trend is an attempt to develop pricing models in which certain aspects of consumer behavior e g asymmetric response to price increases versus price decreases are incorporated this development is quite recent and does offer a large potential a third dominant direction is the use of game theoretic models for developing equilibrium pricing strategies

agent based spatial models applied to agriculture a simulation tool for technology diffusion resource use changes and policy analysis abstract this paper presents a spatial multi agent programming model which has been developed for assessing policy options in the diffusion of innovations and resource use changes unlike conventional simulation tools used in agricultural economics the model class described here applies a multi agent cellular automata ca approach by using heterogeneous farm household models and capturing their social and spatial interactions explicitly the individual choice of the farm household among available production consumption investment and marketing alternatives is represented in recursive linear programming models adoption constraints are introduced in form of network threshold values that reflect the cumulative effects of experience and observation of peers experiences the model s economic and hydrologic components are tightly connected into a spatial framework the integration of economic and hydrologic processes facilitates the consideration of feedback effects in the use of water for irrigation the simulation runs of the model are carried out with an empirical data set which has been derived from various data sources on an agricultural region in chile simulation results show that agent based spatial modelling constitutes a powerful approach to better understanding processes of innovation and resource use change

socio economic development and software piracy an empirical assessment the high rate of software piracy is a growing concern for software developers as well as businesses and governments it is argued here that the piracy rate is influenced by expected benefits and costs to the pirates a model is developed using a set of variables that may affect such benefits and costs and hence piracy rate in a country and tested for a large sample of 53 countries the results of this paper suggest that the existing socio economic conditions and the lack of proper institutions in developing and emerging economies may be responsible for high software piracy rates one may therefore infer that the current trends of globalization and socio economic development may help software piracy in developing countries

a comparison of alternative models for the demand for medical care we have tested alternative models of the demand for medical care using experimental data the estimated response of demand to insurance plan is sensitive to the model used we therefore use a split sample analysis and find that a model that more closely approximates distributional assumptions and uses a nonparametric retransformation factor performs better in terms of mean squared forecast error simpler models are inferior either because they are not robust to outliers e g anova anocova or because they are inconsistent when strong distributional assumptions are violated e g a two parameter box cox transformation

the economics of wheat research in developing countries the one hundred million dollar puzzle abstract currently 1 150 scientists are carrying out wheat improvement research in developing countries with an annual budget of around 100 million because of the recent reduction in agricultural research budgets this study marshalls evidence from 71 wheat research programs in 35 developing countries to address the following puzzle what is the optimal size type and location of wheat research programs in the developing world the analysis reveals that if research spillins are taken into consideration almost half of the wheat improvement programs in developing countries are inefficient the efficiency of wheat research in many national agricultural research systems can be increased by reducing the size of research programs consolidating state and federal research programs and shifting from wheat breeding research to capturing spillins from other countries and from the international maize and wheat improvement center cimmyt

skimming or penetration strategic dynamic pricing for new products current complex dynamic markets are characterized by numerous brands each with multiple products and price points and differentiated on a variety of product attributes plus a large number of new product introductions this study seeks to analyze dynamic pricing paths in a highly complex branded market consisting of 663 products under 79 brand names of digital cameras the authors develop a method to classify dynamic pricing strategies and analyze the choice and correlates of observed pricing paths in the introduction and early growth phase of this market the authors find that despite numerous recommendations in the literature for skimming or penetration pricing market pricing dominates in practice in particular the authors find five patterns skimming 20 frequency penetration 20 frequency and three variants of market pricing patterns 60 frequency where new products are launched at market prices skimming pricing launches the new product 16 above the market price and subsequently increases the price relative to the market price penetration pricing launches the new product 18 below the market price and subsequently lowers the price relative to the market price firms exhibit a mix of these pricing paths across their portfolios the specific pricing paths correlate with market firm and brand characteristics such as competitive intensity market pioneering brand reputation and experience effects the authors discuss managerial implications

estimating health demand for an aging population a flexible and robust bayesian joint model in this paper we analyse two frequently used measures of the demand for health care namely hospital visits and out of pocket health care expenditure which have been analysed separately in the existing literature given that these two measures of healthcare demand are highly likely to be closely correlated we propose a framework to jointly model hospital visits and out of pocket medical expenditure furthermore the joint framework allows for the presence of non linear effects of covariates using splines to capture the effects of aging on healthcare demand sample heterogeneity is modelled robustly with the random effects following dirichlet process priors with explicit cross part correlation the findings of our empirical analysis of the u s health and retirement survey indicate that the demand for healthcare varies with age and gender and exhibits significant cross part correlation that provides a rich understanding of how aging affects health care demand which is of particular policy relevance in the context of an aging population

the impact of nearly universal insurance coverage on health care utilization evidence from medicare the onset of medicare eligibility at age 65 leads to sharp changes in the health insurance coverage of the u s population these changes lead to increases in the use of medical services with a pattern of gains across socioeconomic groups that varies by type of service while routine doctor visits increase more for groups that previously lacked insurance hospital admissions for relatively expensive procedures like bypass surgery and joint replacement increase more for previously insured groups that are more likely to have supplementary coverage after 65 reflecting the relative generosity of their combined insurance package under medicare