theoretical and empirical specifications issues in travel cost demand studies the ultimate objective of empirical travel cost demand studies is to obtain an estimate of the welfare derived from utilizing outdoor recreational resources thus it is apparent that travel cost demand equations must be linked to utility maximization deyak and smith freeman bockstael and mcconnell hanemann bockstael hanemann and strand we specify a model of utilitymaximizing recreation demand behavior which postulates that individuals choose the total number of days that they wish to spend at the recreation site this total number of recreation days is the product of the number of trips

endogenous on site time in the recreation demand model careful modeling of on site time may substantially improve estimates of the bene fits of recreational visits using the travel cost method especially when on site time is endoge nous this paper reviews the theory of endoge nous on site time and shows how the theory may apply to the random utility model rum an empirical example of a two level nested choice model of sport fishing in southcentral alaska il lustrates a discussion of the relative advantages of the different ways to specify endogenous on site time jel q26

a utility consistent combined discrete choice and count data model assessing recreational use losses due to natural resource damage abstract a two stage budgeting approach can often be taken when analyzing consumer choice situations in this paper we examine the particular situation where a consumer makes purchases of a discrete commodity of which there are a number of brands in the first stage the consumer decides how many purchases to make in the second stage the consumer decides how to allocate these purchases across brands our econometric approach to this type of situation uses a utility consistent combined discrete choice and count data model the second stage which is specified as a multinomial choice model produces a price index for the commodity which is used to estimate the first stage which is specified as a count data model we apply the model to recreational demand behavior in alaska in order to estimate the welfare losses suffered by recreational users due to the exxon valdez oil spill these results may provide useful input to government agencies attempting to estimate the appropriate level of taxes fines or regulations for deterring damage to the environment

spatial boundaries and choice set definition in a random utility model of recreation demand we are concerned with the definition of choice set used in random utility models of recreation demand in particular we are concerned with the spatial boundaries used to define choice sets in this paper using a model of day trip fishing in maine we examine the sensitivity of parameter and welfare estimates to changes in the spatial boundary we find that there exists some threshold distance beyond which adding more sites to the choice set has negligible effects on the estimation results

a repeated nested logit model of atlantic salmon fishing participation and site choice for atlantic salmon fishing are modeled in the context of a repeated three level nested logit model consumer s surplus measures are derived for different levels of species availability in the penobscot river the most important salmon river in new england for comparison six other travel cost models are estimated these include restrictive cases of the nested logit model a partial demand model and two single site demand models comparisons across these models indicate the importance of modeling the participation decision including income effects and of adopting a nested logit structure rather than a single level logit structure

estimating the cost of leisure time for recreation demand models abstract in this paper we propose a method of determining the opportunity cost of leisure time with an empirical recreation demand application typically the opportunity cost of leisure time is assumed to be some fraction of the wage rate this practice has limitations first it assumes that individuals can trade time for money at their wage second it offers no guidance about how to value the time of an individual who is not in the labor force this paper proposes a method of determining this cost that does not suffer from these drawbacks an empirical example is provided which demonstrates the proposed approach and contrasts it with commonly applied approaches

the individual travel cost method with consumer specific values of travel time savings the treatment of the opportunity cost of travel time in travel cost models has been an area of research interest for many decades our analysis develops a methodology to combine the travel distance and travel time data with respondent specific estimates of the value of travel time savings vtts the individual vtts are elicited with the use of discrete choice stated preference methods the travel time valuation procedure is integrated into the travel cost valuation exercise to create a two equation structural model of site valuation since the travel time equation of the structural model incorporates individual preference heterogeneity the full structure model provides a travel cost site demand model based upon individualized values of time the methodology is illustrated in a study of recreational birdwatching more specifically visits to a stork village in poland we show that the usual practice of basing respondents vtts on 1 3 of their wage rate is largely unfounded and propose alternatives including a separate component of the travel cost survey aimed at valuation of respondents vtts or as a second best asking if they wish if their journey was shorter and for those who do use full hourly wage as an indicator of their vtts

a latent segmentation approach to a kuhn tucker model an application to recreation demand abstract in this paper we extend the latent segmentation approach to the kuhn tucker kt model the proposed approach models heterogeneity in preferences for recreational behavior using a utility theoretical framework to simultaneously model participation and site selection decisions estimation of the latent segmentation kt model with standard maximum likelihood techniques is numerically difficult because of the large number of parameters in the segment membership functions and the utility function for each latent segment to address this problem we propose the expectation maximization em algorithm to estimate the model in the empirical section we implement the em latent segmentation kt approach to analyze a southern california beach recreation data set our empirical analysis suggests that three groups exist in the sample using the model to analyze two hypothetical beach management policy scenarios illustrates different welfare impacts across groups

the opportunity cost of travel time in recreation demand models deciding how to allocate forage among animals is a fundamentally important process in range management the wisdom of these decisions can be enhanced by estimating the marginal value of forage needed by competing species we present a method for

technical efficiency and productivity of maize producers in eastern ethiopia a study of farmers within and outside the sasakawa global 2000 project abstract this paper investigates the technical efficiency of two samples of maize producers in eastern ethiopia one involving farmers within the sasakawa global 2000 project and the other involving farmers outside this program the study uses stochastic frontier production functions in which the technical inefficiency effects are assumed to be functions of the age and education of the farmers together with the time spent by extension advisers in assisting farmers in their agricultural production operations for the cross sectional data obtained for the 1995 96 agricultural year cobb douglas stochastic frontiers are found to be adequate representations of the data given the specifications of the translog stochastic frontiers for farmers within and outside the project the empirical results indicate that farmers within the sg 2000 project are more technically efficient than farmers outside the project relative to their respective technologies the mean frontier output of maize for farmers within the sg 2000 project is significantly greater than that for the farmers outside the project

contract farming and smallholder outgrower schemes in less developed countries abstract some studies of outgrower schemes involving smallholders and public or private corporations in less developed countries suggest the potential value of such arrangements in facilitating transfer of technology access to markets and other benefits for growers a diverse literature is surveyed to see what economic and political questions have been raised which have a bearing on the issue of grower welfare in some cases existing literature or the author s own research provides adequate answers to the questions raised in others the need for further research is indicated some possible directions and methodologies for systematic comparative studies are suggested

a semi parametric estimator for revealed and stated preference data an application to recreational beach visitation abstract we present a semi parametric approach for jointly estimating revealed and stated preference recreation demand models the discrete factor method dfm allows for correlation across demand equations and incorporates unobserved heterogeneity our model is a generalized negative binomial with random effects the random effect is composed of a discrete representation of unobserved heterogeneity and a factor loading that translates the heterogeneity measure into a demand effect our empirical application is to beach recreation demand in north carolina statistical evidence supports our dfm specification which imposes less restriction on model dispersion and incorporates unobserved heterogeneity in a flexible manner elasticity estimates are smaller than those derived from models with parametric specifications for unobserved heterogeneity and welfare estimates are slightly larger and less precise while parametric models clearly dominate if the specification of unobserved heterogeneity is correct the semi parametric dfm provides a flexible alternative in cases where mis specification is a potential problem

farm household efficiency in bangladesh a comparison of stochastic frontier and dea methods this study compares estimates of technical efficiency obtained from the stochastic frontier approach and the data envelopment analysis dea approach using farm level survey data for rice farmers in bangladesh technical inefficiency effects are modelled as a function of farm specific socioeconomic factors environmental factors and irrigation infrastructure the results from both the approaches indicate that efficiency is significantly influenced by the factors measuring environmental degradation and irrigation infrastructure

improving environmental valuation estimates through consistent use of revealed and stated preference information abstract environmental valuation data from stated and revealed preference methods are integrated into a unified model of preferences for environmental quality improvement that identifies the use and nonuse components of the total value estimate this articulates clearly what parts of the total value estimate come from each type of data and permits tests of whether estimated preferences satisfy weak complementarity between the environmental good of interest and related private goods the statistical advantages of using more information for the valuation problem are exploited while retaining flexibility to identify value estimates from any individual method of analysis

signals or noise explaining the variation in recreation benefit estimates this paper uses meta analysis to summarize the benefit estimates derived from travel cost recreation demand models after reviewing approximately 200 published and unpublished studies prepared from 1970 to 1986 77 were found to report either consumer surplus estimates or sufficient information to derive them using these estimates of the consumer surplus per unit of use from each study it was possible to evaluate the influence of variables describing the site characteristics the activities undertaken at each site the behavioral assumptions and the specification decisions the findings provide clear support for using econometric methods to summarize results from diverse empirical studies they highlight the important research issues in model development and offer a consistency check to the procedures used in benefit transfer analyses for policy evaluations

valuing time in travel cost demand analysis an empirical investigation the opportunity cost of time is usu ally a significant part of the price variable in the travel cost demand model thus its accurate mea surement is important to the estimation of demand and benefit valuation for nonmarket resources this paper empirically tests models which assume that income is the basis for opportunity time cost with an alternative pooled model based on a disequi librium labor market for some recreationists ac ceptance of the hypothesis that disequilibrium mod els may be necessary for some individuals implies increased survey information requirements so that the appropriate model can be applied to each indi vidual jel q21

omitted cross price variable biases in the linear travel cost model correcting common misperceptions the essence of the travel cost method is that the combination of the number of visits to a site and the round trip travel costs for each recreationist traces out a demand relationship since the geographic location of the recreationist s residence exerts a kind of experimental control which forces the more distant consumer to bear higher travel and related costs these travel costs are used as proxies for prices in estimating demand for the site s services clawson 1959 has presented the two step method for valuing a single site s services however it has been pointed out in the literature that single and isolated recreation sites very rarely exist and the failure to include prices for alternative sites in the demand equation leads to biased estimates for the value of the resource under consideration the literature contains some misconceptions about the direction of the bias consider quotations from two frequently cited studies

the opportunity cost of travel time as a noisy wage fraction few issues are more important to welfare estimation with recreation demand models than the specification of the opportunity cost of travel time the two most common approaches to specifying this cost treat it as a fixed fraction of the recreationist s wage and either estimate the fraction done infrequently or assume it takes some value done commonly with references to results from the commute time literature used to justify the latter however these approaches lack firm conceptual rationales and the consequences of using them are not fully understood recognizing that information limitations often preclude more general approaches we use a joint recreation travel labor supply model to show that under relatively modest assumptions the opportunity cost of travel time can be expressed as a wage fraction with noise this formulation is straightforward to implement as part of random parameters based recreation demand models we then evaluate the welfare consequences of using the two approaches noted above which are special cases of the noisy wage fraction specification our results suggest that the more critical restriction to relax in opportunity cost of travel time specifications is the absence of noise rather than the specific level of the wage fraction

estimating social welfare using count data models an application to long run recreation demand under conditions of endogenous stratification and truncation this paper develops a negative binomial model of recreation demand that corrects for both truncation and endogenous stratification this approach recovers the demand associated with the general population not just the users of the site this model demonstrates the importance of the joint nature of the population s latent demand for trips and the consumer surplus associated with those trips the empirical results provide an estimate of the willingness to pay by washington state residents for hiking opportunities in the cascade mountain range these results are used to forecast total trips and willingness to pay over the next forty years copyright 1995 by mit press

recreation demand choices and revealed values of leisure time i introduction at least since the work of becker 1965 it has been recognized widely that time may play an important role in consumer demand one of the areas where this may be most significant empirically is in the valuation of natural resource amenities through their associated recreation demands a principal reason is that recreation is a time intensive commodity so that the value of the time spent in recreation would be expected to play a large role in its overall value the potential bias to consumer s surplus estimates of the net economic value of recreation from excluding time prices from the demand model has been recognized from the outset for example by knetsch 1963 and clawson 1959 to incorporate time into recreation demand models researchers have generally adopted the practice suggested by mcconnell 1975 of defining the full price of recreation as the money cost of a trip plus its monetized time cost though the use of full budgets also called for by the becker approach is less widespread bockstael et al 1987 pointed out quite clearly that both full budgets and full prices are required in the demand function if the recreationist is jointly choosing labor supply with recreation at an exogenous marginal wage but that the structure of demand was unclear if the individual was not making such marginal labor supply choices i e if he or she was working fixed hours subsequently larson and shaikh 2001 showed that the full prices full budgets specification is sufficient to satisfy the constraints on demand parameters that arise because choice is made subject to two binding constraints regardless of the individual s position in the labor market they also pointed out that models that use full prices but only money income in effect ignoring the role of time as a resource constraint cannot be consistent with the requirements of choice subject to two constraints although the outlines of how time should enter the structure of demand are becoming clear a major unresolved issue is how to determine its value in practice several studies have followed the basic logic of becker s early work assuming that the opportunity cost of recreation time i e the value of other time forgone in favor of recreation is an exogenous parameter such as the average wage rate or more commonly some fraction thereof this fraction is either chosen arbitrarily or estimated as part of the recreation demand model as in cesario 1976 mcconnell and strand 1981 and smith et al 1983 such assumptions may be erroneous for a variety of reasons assuming the average wage is the appropriate opportunity cost of time presumes that the individual faces no constraints on hours worked derives no utility or disutility from work and has a linear wage function as has been noted by chiswick 1967 bockstael et al 1987 and smith et al 1983 this is unlikely to be true for many people assuming some constant fraction of the wage is the opportunity cost of time especially an arbitrarily chosen fraction also seems likely to be incorrect for most people for all of these reasons an individual s average wage does not necessarily reveal anything about the shadow value of discretionary leisure time either as an upper or lower bound in a recent advance feather and shaw 2000 adapted the heckman 1974 labor supply model to include information supplied by recreationists about their labor supply status in particular whether they felt under or over employed relative to their desired number of hours this information is used to identify subgroups in the data for which the shadow value of leisure time is less than the wage or more than the wage which helps in the estimation of both a wage function and a shadow value of leisure time function this approach produces individual specific estimates of the opportunity cost of leisure time based on their demographics and labor market decisions which are used in a subsequent recreation demand analysis

on site time in the demand for recreation the standard travel cost model has treated on site time ambiguously over the years this paper shows how to handle on site time by exploring the implications of two assumptions in the travel cost model first people choose the amount of time that they spend on a site and second the time spent on site is exogenous this paper uses a duality result to show that when on site time is chosen the standard travel cost demand function takes a particularly simple form with slight modification standard estimation and welfare calculations continue to hold

estimation and welfare calculations in a generalized corner solution model with an application to recreation demand the kuhn tucker model of wales and woodland 1983 provides a utility theoretic framework for estimating preferences over commodities for which individuals choose not to consume one or more of the goods due to the complexity of the model however there have been few applications in the literature and little attention has been paid to the problems of welfare analysis within the kuhn tucker framework this paper provides an application of the model to the problem of recreation demand in addition we develop and apply a methodology for estimating compensating variation relying on monte carlo integration to derive expected welfare changes

short run constraints and the increasing marginal value of time in recreation leisure activities such as local recreation trips usually take place in discrete blocks of time that are surrounded by time devoted to other commitments it can be costly to transfer time between blocks to allow for longer outings these observations affect the value of time within those blocks and suggest that traditional methods for valuing time using labor markets miss important considerations this paper presents a new model for time valuation that uses non employment time commitments to infer the shadow value of time spent in recreation a unique survey that elicited revealed and stated preference data on household time allocation is used to implement the model the results support the conclusion that there is an increasing marginal value of time for recreation as the trip length increases

accounting for stochastic shadow values of time in discrete choice recreation demand models abstract in this paper a discrete choice recreation demand model that explicitly accounts for a stochastic shadow value of time function is proposed using data from a survey of san diego beach users the stochastic shadow value of time labor supply and beach choice are jointly estimated results from this joint estimation approach are compared with the familiar two step approach that estimates labor supply first and uses predicted values of time in the recreational site choice model the approaches produce markedly different welfare measures with the two step model which does not account for unobserved variability of time values predicting significantly higher values a monte carlo simulation illustrates how ignoring the stochastic nature of shadow value of time in discrete choice recreation demand models can bias model parameters and hence welfare estimates

time and the recreational demand model in this paper a theoretically consistent approach to including time costs in recreational demand models is developed the demand model is conditional on the recreationist s labor market situation for individuals at corner solutions in the labor market utility maximization is subject to two constraints leading to a demand function with travel costs and travel time as independent variables with interior solutions in the labor market time is valued at the wage rate and combined with travel costs to produce one full cost variable in an illustration welfare measures based on the new model are estimated for a sample of sportfishermen

factors affecting the technical efficiency among smallholder farmers in the slash and burn agriculture zone of cameroon abstract this paper estimates technical efficiency among small holder farmers in the slash and burn agriculture zone of cameroon and identifies sources of inefficiency using detailed survey data obtained from 450 farmers over 15 villages throughout 2001 2002 growing season we find that the mean levels of technical efficiency are 77 73 and 75 respectively for groundnut monocrop maize monocrop and maize groundnut farming systems suggesting existence of substantial gains in output and or decreases in cost with available technology and resources the efficiency differences are explained significantly by credit soil fertility social capital distance of the plot from the access road and extension services policy recommendations are drawn from these findings

technical efficiency of alternative farming systems the case of greek organic and conventional olive growing farms abstract olive growing is a major farming activity in greek agriculture this paper analyzes empirically the technical efficiency of organic and conventional olive growing farms using a stochastic production frontier methodology and a translog functional specification findings indicate that the organic olive growing farms examined exhibit a higher degree of technical efficiency relative to their production frontier than do conventional olive growing farms reasons may include lower profit margins and restrictions on inputs permitted thus forcing organic farmers to be more cautious with input use however both input and output oriented technical efficiency scores are still relatively low for both types of olive farming thus there is considerable scope for cost reducing and farm income improvement in both farming modes this could prove crucial for the long run viability and the future course of the sector

a latent class approach to modeling endogenous spatial sorting in zonal recreation demand models a method for incorporating unobserved heterogeneity into aggregate count data frameworks is presented and used to control for endogenous spatial sorting in zonal recreation models the method is based on latent class analysis which has become a popular tool for analyzing heterogeneous preferences with individual data but has not yet been applied to aggregate count data the method is tested using data on backcountry hikers for a southern california study site and performs well for relatively small numbers of classes the latent class model produces substantially smaller welfare estimates compared to a constrained version that assumes homogeneity throughout the population

migrant labor and farm technical efficiency in lesotho abstract the rural economy of lesotho is characterized by dependence on circular labor migration to south african mines and declining agricultural output per capita this paper attempts to improve the understanding of the relationship between circular labor migration and agricultural production by comparing the technical efficiency of farms that supply migrant laborers with that of farms that do not through analysis of the relative technical efficiency of these two farm categories conclusions are drawn concerning the likely impact of changing migration patterns on the agricultural sector

identifying demand parameters in the presence of unobservables a combined revealed and stated preference approach we develop a combined revealed and stated preference approach to identify discrete choice demand parameters in the presence of unobserved determinants of choice our approach overcomes difficulties associated with small choice sets multicollinearity and endogeneity that arise with revealed preference approaches to illustrate our framework we revisit two canadian moose hunting datasets our empirical results suggest the potential gains from fusing revealed and stated preference data but they also suggest its limitations when the data generating processes for the data sources differ

valuing a fishing day an application of a systematic varying parameter model deciding how to allocate forage among animals is a fundamentally important process in range management the wisdom of these decisions can be enhanced by estimating the marginal value of forage needed by competing species we present a method for

profit efficiency among bangladeshi rice farmers abstract production inefficiency is usually analyzed by its three components technical allocative and scale efficiency in this study we provide a direct measure of production efficiency of the bangladeshi rice farmers using a stochastic profit frontier and inefficiency effects model the data which are for 1996 include seven conventional inputs and several other background factors affecting production of modern or high yielding varieties hyvs of rice spread across 21 villages in three agro ecological regions of bangladesh the results show that there are high levels of inefficiency in modern rice cultivation the mean level of profit efficiency is 77 suggesting that an estimated 23 of the profit is lost due to a combination of technical allocative and scale inefficiency in modern rice production the efficiency differences are explained largely by infrastructure soil fertility experience extension services tenancy and share of non agricultural income

measuring the cost of time in recreation demand analysis an application to sportfishing since the work of cesario and knetsch economists have recognized that the opportunity cost of time plays an important role in determining the demand for outdoor recreation the opportunities one has for spare time are more significant for consumption of time intensive outdoor recreation activities than for other commodities especially nondurables bishop and heberlein illustrate the overwhelming importance of time costs to final recreational values total consumer surplus is nearly four times as large when time costs are added at half the income rate as when time costs were set at zero p 21 despite the recognition economists have neither successfully integrated the costs of time with the methods of recreational demand analysis nor reached a consensus on how it should be measured brown charbonneau and hay state finally the apparently crucial importance of how opportunity cost of time is handled needs further work while we are convinced it is an appropriate concept exactly how it should be included and measured s remains to be determined p 24 several approaches have been taken to include it in the travel cost method one approach brown and nawas gum and martin suggests that time in transit be considered as a separate independent variable another approach bishop and heberlein brown charbonneau hay nicols bowes dwyer cesario and knetsch measures the cost of time and adds it to other costs several approaches have been suggested to measure time costs one approach is simply to choose an hourly wage e g 2 00 per hour or perhaps the minimum wage rate a more flexible but still ad hoc approach is to use some proportion of the individual s wage rate as the opportunity cost of time nichols bowes dwyer the proportion is usually taken from independent studies and used to value the travel time this approach is better than using a constant opportunity cost of time because it allows variation across individuals it suffers because the choice of the percentage of the wage rate is arbitrary independent of the sampled population cesario has discussed the consequences of ignoring time costs and the differences in values arising from alternative measurement approaches in this paper we argue that the opportunity cost of time is some proportion of the individual s market wage rate or income per hour and that this proportion can be determined from sample data this method permits the proportion to vary from one study to another rather than imposing either an arbitrary estimate or one from a sample different from the study s sample

recreation demand models with taste differences over people we estimate random parameter logit models of anglers choice of fishing site the models generalize logit by allowing coefficients to vary randomly over anglers rather than being fixed the models do not exhibit the restrictive independence from irrelevant alternatives property of logit and can represent any substitution pattern estimation explicitly accounts for the fact that the variation in coefficients over anglers induces correlation in unobserved utility over trips by the same angler willingness to pay for improved fish stock and the value to anglers of specific sites are calculated from the models and compared with the estimates obtained from a standard logit model

periodic review inventory systems with fixed order cost and uniform random yield abstract we consider periodic review stochastic inventory control problems with both fixed order cost and uniform random yield our objective is to characterize some structural properties of the optimal policies so that efficient approaches can then be established towards finding an optimal policy in particular we provide a lower and upper bound structure for the optimal policy at the beginning of any period such that it is optimal not to order anything if the initial stock level is above the upper bound and it is optimal to order a positive quantity if the initial stock level is below the lower bound where the optimal quantity can be found efficiently for any initial stock level in between the upper and lower bounds in each period a partial characterization of the optimal policy is provided furthermore we show that the optimal order quantity is monotonically decreasing in the initial stock level in any period and this will help the search for the optimal order quantity at any initial stock level in addition we illustrate a few interesting phenomena about the behavior of an optimal policy these phenomena show that the structure of the optimal policy for this problem is in general significantly different from that for the traditional periodic review inventory control problems with certain yield and fixed order cost

productivity growth technical progress and efficiency change in industrialized countries this paper analyzes productivity growth in 17 oecd countries over the period 1979 1988 a nonparametric programming method activity analysis is used to compute malmquist productivity indexes these are decomposed into two component measures namely technical change and efficiency change we find that u s productivity growth is slightly higher than average all of which is due to technical change japan s productivity growth is the highest in the sample with almost half due to efficiency change jel c43 d24 in this paper we apply recently developed

a demand theory for number of trips in a random utility model of recreation we present a simple random utility model of recreation site choice that incorporates an aggregate demand function for number of trips during a season we derive the trip demand function using conventional demand theory and use it to calculate seasonal welfare changes due to improvements in site characteristics or addition of new sites the model is based on bockstael et al s participation function

modeling recreation demand in the presence of unobservable travel costs toward a travel price model an important issue in the application of travel cost models is the construction of a travel cost variable this paper develops an econometric approach that views travel costs as an unobserved latent variable the latent variable approach utilizes indicators to capture the role of individual travel costs in recreational demand models the latent variables approach has at least two advantages over conventional approaches one the indicators can include both traditional components such as time and distance and non traditional components such as the scenic beauty second the estimation procedure results in each indicator being valued in dollar terms

market access by smallholder farmers in malawi implications for technology adoption agricultural productivity and crop income abstract in malawi maize is the major crop and food staple given limited off farm employment opportunities much needed increases in household income for improving food security must come from gains in agricultural productivity through better technology and more profitable crops in the past hybrid maize and more recently tobacco were promoted by policy for increasing smallholder income an analysis of determinants of adoption of these two crops and related income effects is presented apart from factor endowment and exposure to agroecological risks differences in the household s access to financial and commodity markets significantly influence its cropping shares and farm income