instability in short run adjustments to purchasing power parity results for selected latin american countries according to the theory of purchasing power parity ppp there is a tendency toward equalization of different countries price levels in common currency terms however even assuming that a long run ppp relationship exists its relevance for policy makers in less developed countries ldcs will depend not only on the average speed of adjustment toward this relationship but also on the variability of such short run adjustments we present evidence of extreme volatility in adjustments toward ppp for four latin american countries based on time varying parameter estimates of error correction models

more on estimation risk and simple rules for optimal portfolio selection for the risk averse investor consideration of estimation risk is important in selecting an expected utility maximizing portfolio it has previously been shown that the composition of the tangency portfolio is unaffected by the recognition of estimation risk if the full covariance model is used alternatively if the market model is used the composition of the tangency portfolio has been shown to be affected by the recognition of estimation risk however as is demonstrated in this paper the effect will generally not be as substantive as previously believed and in many situations can be safely ignored in order to determine the composition and location of an efficient frontier from which an optimal portfolio will be selected the investor must employ estimates of expected returns variances and covariances for the set of securities under consideration if the investor simply treats the estimated parameter values for the securities as true parameter values then estimation risk will have been ignored and as shown by barry 1 and klein and bawa 14 15 a suboptimal portfolio will most likely have been selected bawa brown and klein 6 and klein and bawa 14 discuss the effects of estimation risk on the selection of an optimal portfolio from a set of risky assets and note that the location but not the composition of the efficient frontier changes when estimation risk is recognized if security returns are generated by a stationary multivariate normal distribution for which the investor has a diffuse prior furthermore brown 8 has shown these results to be robust for severe misspecification of the underlying multivariate distribution of returns e g assuming it to be normal when in actuality it is student t with small degrees of freedom this paper is concerned with the effects of estimation risk on the composition of the tangency portfolio derived from a set of risky assets and a risk free asset under the assumption that the investor has a diffuse prior 1 barry 2 bawa and brown 4 and brown 7 have shown analytically that the composition of the tangency portfolio is unaffected by estimation risk if the full covariance model is used chen and brown 10 have expanded upon the work of brown 9 and have argued that if security returns are generated by the market model then the composition of the tangency portfolio will be substantively different when estimation risk is recognized

hedging production risk with options the expected utility maximization problem is solved for producers with both price and production uncertainty who have access to both futures and options markets introduction of production uncertainty alters the optimal futures and options position and almost always makes it optimal for the producer to purchase put options and to underhedge on the futures market simulation results lend support to the practice of hedging the minimum expected yield on the futures market and hedging remaining expected production against downside price risk using put options the results are strengthened if the producer expects local production to influence national prices and if risk aversion is higher at low income levels

estimating willingness to pay for housing characteristics an application of the ellickson bid rent model abstract the purpose of this paper is to estimate willingness to pay for housing characteristics using the discrete choice bid rent framework developed by b ellickson j urban econom 9 56 79 1981 and modified by s r lerman and c r kern j urban econom 13 358 363 1983 the paper provides an initial empirical test of the lerman and kern modifications using household level data from bogota colombia the results of the model are evaluated by comparing forecasted bid rents to actual rents and forecasted dwelling occupants to actual occupants by examining the demand prices which emerge from the analysis and by comparing the results to previous housing demand research which uses a hedonic type approach to analyze identical data the findings of the study show that the bid rent model works reasonably well in its predictions and in its estimates of the demand for attributes and in some ways it may perform better than a hedonic type model in forecasting the demand for housing attributes

national price levels purchasing power parity and cointegration a test of four high inflation economies abstract the time series properties of exchange rates and wholesale prices from four high inflation countries show some evidence in support of purchasing power parity tests for stationarity of real exchange rates and cointegration among price and exchange rate variables are presented for argentina brazil chile and israel during the 1970s and 1980s error correction models describe the mechanism of adjustment to long run equilibrium

exchange rate economics 1986 in the past fifteen years key exchange rates have moved in larger and more persistent ways than advocates of flexible rates in the late 1960s would have left anyone free to imagine certainly there was no expectation of constancy for nominal exchange rates but real exchange rate movements of 30 or forty percent were definitely not suggested as a realistic possibility moreover where these large movements did occur they did not obviously appear to be connected with fundamentals and hence seemed difficult to explain in terms of the exchange rate theories at hand the persistence of rate movements was as surprising as the rapid unwinding of apparent misalignments when they did ultimately occur the past fifteen years provide a natural dividing line between the keynesian and monetary approaches of the 1960s and the more recent analysis that takes into account exchange rate expectations and portfolio issues which took off in the early 1970s as well as the brand new approaches that concentrate on partial equilibrium microeconomics to review these ideas the paper starts with a brief look at the u s experience with flexible exchange rates from there it proceeds to the mundell fleming model as a comprehensive framework of analysis the following sections deal with persistent effects of policy disturbances links between exchange rates and prices the political economy of exchange rate movements and the question of policies toward excess capital mobility this abstract was borrowed from another version of this item

hedonic theory bid rents and willingness to pay some extensions of ellickson s results abstract an alternative to ellickson s multinomial logit model of household bids for dwelling units is derived by making use of observable information on the price paid by the winning bidder the alternative specification makes it possible to estimate willingness to pay for housing attributes which cannot be obtained from ellickson s model some methodological issues arising from ellickson s method of grouping households are also examined

bidding models of housing markets abstract the bid rent model which is the standard bidding model of housing markets fails to take account of three important characteristics of the bidding process that operates in these markets the prices of houses are established through sequential bidding so that sellers do not necessarily accept the highest bids that might be made for their houses ignorance of the market may lead potential buyers to make bids that are either higher or lower than the ones they would make if they had complete information and the distribution of bids for a house is truncated at the seller s asking price this paper describes a bidding model that incorporates these characteristics of housing markets the new model and the standard model are estimated econometrically and tested against one another using data from the baltimore maryland area the test results indicate strong rejection of the standard model it is concluded that the new model provides a better description of the operation of housing markets than does the standard model

exchange rate rules and macroeconomic stability this paper discusses exchange rate rules in their role as macroeconomic instruments we abstract throughout from the trend part of exchange rate behaviour a crawling peg necessitated by differences in trend inflation and emphasise instead the implications of exchange rate rules in providing flexibility of real wages or in affecting the stability of output or prices

bivariate garch estimation of the optimal commodity futures hedge six different commodities are examined using daily data over two futures contract periods cash and futures prices for all six commodities are found to be well described as martingales with near integrated garch innovations bivariate garch models of cash and futures prices are estimated for the same six commodities the optimal hedge ratio ohr is then calculated as a ratio of the conditional covariance between cash and futures to the conditional variance of futures the estimated ohrs reveal that the standard assumption of a time invariant ohr is inappropriate for each commodity the estimated ohr path appears non stationary which has important implications for hedging strategies

estimation of the bid rent function with the usage decision model abstract this paper examines whether the bid rent function model is a valid description of a mechanism of the urban land market we estimate the function that decides land usage and price using the full information maximum likelihood fiml it finds that land usage on average follows the rule that is consistent with the bid rent function model whichever usage outbids the others occupies the land however the evidence also suggests that there is a systematic departure from the model namely the distance from the second city center may directly affect land usage even though it is not reflected in land prices

state intervention for food price stabilisation in africa can it work abstract although its arguments may have more general applicability this paper discusses the desirability and options for the stabilisation of staple food prices principally in eastern and southern africa it addresses three broad questions i why is stabilisation of food grain prices desirable ii what is technically feasible and iii can the governance and trade issues thrown up by suggested mechanisms be solved it considers a number of options for price stabilisation assessing the strengths and weaknesses of each and suggesting situations in which each may be appropriate

countercyclical safety nets for the poor and vulnerable abstract relatively little is known about how government safety net programs insure against low consumption and stabilize asset bases compared to what is known about their role in transferring income the insurance function requires a flexible budget that can be scaled up rapidly to meet unanticipated circumstances safety nets serving an insurance function also differ from other transfer programs in their targeting they need to determine transitory need rather than more chronic correlates of poverty moreover insurance safety nets need a more flexible implementation strategy than do more permanent programs this paper reviews these issues from the perspective of low income countries

equilibrium pricing and portfolio composition in the presence of uncertain parameters abstract we analyze the effect of parameter uncertainty on equilibrium asset prices for the symmetric case when the amount of estimation risk is the same for all securities the existing literature argues that parameter uncertainty is largely irrelevant for equilibrium our results differ we find that symmetric estimation risk affects equilibrium values of relative asset prices expected returns market weights and betas

co integration error and purchasing power parity between canada and the united states the concept of cointegration and the associated error correction representation of a dynamic process see r f engle and c w g granger 1987 is applied to the purchasing power parity relationship between canada and the united states the results are supportive of purchasing power parity as a long run equilibrium relationship between the canadian dollar american dollar exchange rate the purchasing power parity relationship is maintained although with different dynamic mechanisms during both fixed and flexible exchange rate regimes

purchasing power parity in the short and long run a reappraisal of the post 1973 evidence in this paper an attempt is made to separate the short run and long run aspects of the purchasing power parity ppp relationship using the techniques of band spectral regression and cointegration for eight industrialized countries the long run ppp is first tested for all the eight countries with reference to their nominal bilateral exchange rates vis a visthe us dollar for five european currencies the analysis is repeated with respect to the deutschmark with a separate consideration of the post ems period in the concluding sections possible reasons for ppp deviations are examined

an empirical examination of long run purchasing power parity as theory of international commodity arbitrage an empirical analysis of long run purchasing power parity ppp as a theory of international commodity arbitrage between uk and us prices and the sterling us dollar exchange rate for the period 1975 1980 is presented econometric techniques concerning the cointegration of economic time series are applied to a sample of 35 manufactured commodities which in 1977 constituted approximately a quarter of the net output of all manufacturing industry in great britain our results are extremely unfavourable to the ppp hypothesis as a stable long run proportionality between exchange rates and disaggregated prices

developing agricultural markets in sub saharan africa organic cocoa in rural uganda abstract this article investigates the process of development in a traditional african export market focusing on a contract farming scheme for organic cocoa in rural uganda based on a repeated household survey we measure the impact of the scheme on the income of participants and the economic mechanisms behind these effects we find substantial benefits from the scheme driven primarily by the establishment of credible incentives for farmers to adopt technologies which improve cocoa quality there is also evidence of broader trends of market deepening and increased productivity probably due to positive spillovers

policies to promote cereal intensification in ethiopia the search for appropriate public and private roles over the past decade policymakers have been searching for an appropriate blend of public and private sector roles to accelerate the intensification of food staple production smallholder commercialization and sustainable market development in sub saharan africa in ethiopia steps taken to liberalize markets in the 1990s and promote fertilizer and seed packages have yet to generate payoffs in terms of higher cereal yields lower food prices or reduced dependency on food aid this raises concern about the performance of the agricultural sector specifically in terms of the systems for providing improved seed fertilizer credit and extension services this paper examines the evolving roles of the public and private sectors in intensifying cereal production in ethiopia findings suggest that while ethiopia has an admirable record of supporting agriculture its state led policies has now outlived their usefulness these findings for ethiopia offer lessons that are potentially applicable to other sub saharan african countries facing similar challenges

bayes stein estimation for portfolio analysis in portfolio analysis uncertainty about parameter values leads to suboptimal portfolio choices the resulting loss in the investor s utility is a function of the particular estimator chosen for expected returns so this is a problem of simultaneous estimation of normal means under a well specified loss function in this situation as stein has shown the clas sical sample mean is inadmissible this paper presents a simple empirical bayes estimator that should outperform the sample mean in the context of a portfolio simulation analysis shows that these bayes stein estimators provide significant gains in portfolio selection problems

grain price stabilization experiences in asia what have we learned abstract governments in most asian countries used grain price stabilization as a major policy instrument when they embarked on promoting the green revolution the art of public policy making is to know when to introduce government interventions and when to withdraw the common mistake is to forget the withdrawal part leading to unsustainably high costs a dilemma that most asian countries are confronted with today analyzing case studies of six asian countries which have tried to tackle the task in different ways with varying degrees of success eight key lessons can be learned from the more than three decades of food price stabilization in asia times have changed policies and public agencies that may have been appropriate 30 years ago are not optimal today private institutions have strengthened significantly or could be strengthened significantly and should be entrusted for many of the functions that parastatals or other government agencies have traditionally performed holding on to old practices delays reaping the benefits that changing current policies have to offer

determination of the recommended hedging ratio the traditional literature on commodity futures markets defined a hedge as a futures market position which is equal but opposite to the individual s cash market position more recent studies have recognized that the futures market position need not equal the cash market position to constitute a hedge many researchers have theoretically solved for the optimal futures and cash market positions for example heifner johnson ward and fletcher and telser determined the optimal futures and cash market positions simultaneously peck determined the optimal futures market position assuming that the cash market position was given the formulas for the optimal futures and cash holdings differ from study to study because of the different underlying assumptions however general implications can be deduced from these studies concerning the size of the optimal hedging ratio i e the ratio of the optimal futures position to the optimal cash position in this paper it is argued that the optimal hedging ratios consistent with the results obtained by johnson ward and fletcher and telser are identical to the optimal hedging ratio derived byheifner 1972 1973 the exercise provides a major implication for hedging strategy which is consistent with all of these studies that the optimal hedging ratio is independent of the individual s risk aversion even though the optimal positions are themselves not independent of the risk parameter this implication is also valid for the minimum risk hedging ratio derived by johnson ederington and mckinnon finally the optimal hedging ratio in peck remains dependent on the risk parameter because the cash market position is assumed to be given

a quantitative reassessment of the purchasing power parity hypothesis evidence from norway and the united kingdom summary annual data from norway and the united kingdom from 1874 to 1971 are used to reassess the empirical performance of the purchasing power parity ppp doctrine the simple version of the ppp relationship is supported by the data only if different short run dynamics during a floating rate period 1914 1928 is allowed for two sets of factors were found to be important in amending the simple ppp model these were short run cyclical variables affecting the adjustment towards the ppp equilibrium relationship and long run structural factors such as productivity and terms of trade within this expanded model the proportionality between the exchange rate and relative price levels could not be rejected

managing food price risks and instability in a liberalizing market environment overview and policy options abstract managing food price risks and instability is a major challenge in the midst of ongoing food market reforms key findings from the papers in this special volume revolve around five broad areas i the sources and magnitudes of food price instability in different country contexts ii the economic and social costs stemming from price instability iii the lessons from food market reforms to date iv the design of policy reforms in ways that promote efficient and stable market development and protect the interests of the poor and v potential policy responses to food price instability in a liberalizing market environment

a search model of housing market transactions arrive in a temporal sequence if an offer is received a seller must decide whether to accept the current offer or to reject that offer and continue to search it is this strategic choice and the possibility of not receiving an offer that results in extended selling periods and stocks of unsold houses rejection of offers and extended selling periods are to be expected in an uncertain environment where search may be used productively to obtain a higher selling price this paper considers the implications of a search environment for measurement of hedonic prices because an offer is observed only when it is acceptable to the seller sold houses constitute a self selected subsample in a search environment accurate measurement of hedonic prices in this situation may be obtained with the two stage procedure of heckman 3 and lee 5 or the maximum likelihood procedure summarized in amemiya 1 the empirical model presented in section ii is a generalization of the usual hedonic model in the sense that the pricing equation is supplemented with an exchange equation which determines probability of sale the coefficients in each equation provide useful information regarding housing search the coefficients in the pricing equation are marginal attribute prices while the attribute coefficients in the exchange equation are the standardized differences between the marginal attribute prices of buyers and sellers an interesting implication of this model is that attribute variation will not be systematically related to probability of sale if the marginal attribute prices of buyers and sellers equalize thus this model may be used to address two related questions regarding hedonic analysis in a search environment first does competition among buyers and sellers equalize marginal attribute prices in a search environment and second is accurate measurement of hedonic prices affected by the probabilistic nature of sale

estimation risk in farm planning under uncertainty this paper examines the impact of estimation risk on a decision maker s ability to distinguish between the mean variance characteristics of different farm plans the importance of making such distinctions should be clear risk averse decision makers will want to bear risk only if they can be reasonably confident of commensurate increases in expected return when parameters are unknown statistically testing for differences in their estimated values is appropriate an illustration of such tests using data from hazell suggests considerable resources must be devoted toward data generation if normative statements under uncertainty are to be reliable

an alternative test of the hedonic theory of housing markets abstract in this paper the hedonic theory of housing markets is used to generate a multinomial logit model of household behavior in an urban housing market application of hedonic theory to housing markets is by now fairly familiar and a link to multinomial logit has also been established however by emphasizing more heavily the bid price interpretation of hedonic theory this paper develops a new connection to econometric estimation that essentially involves running the usual logit equations in reverse one advantage of this approach is that the link between the logit equations and hedonic theory involves bid price rather than utility functions and this in turn permits the empirical results to be given an extremely clear interpretation furthermore in contrast to the standard logit model the extreme value distribution required to justify the estimation technique emerges endogenously as part of the analysis

food security and storage in the middle east and north africa in times of highly volatile commodity markets governments often try to protect their populations from rapidly rising food prices which can be particularly harsh for the poor a potential solution for food deficit countries is to hold strategic reserves which can be called on when international prices spike but how large should strategic stockpiles be this paper develops a dynamic storage model for wheat in the middle east and north africa mena region where imported wheat dominates the average diet the paper uses the model to analyze a strategy that sets aside wheat stockpiles which can be used when needed to keep domestic prices below a targeted price this paper shows that if the target is set high and reserves are adequate the strategy can be effective and robust contrary to most interventions strategic storage policies are counter cyclical and when the importing region is sufficiently large a regional policy can smooth global prices this paper shows that this is the case for the mena region nevertheless the policy is more costly than the pro cyclical policy of a targeted intervention that directly offsets high prices with a subsidy similar to food stamps

a limiting joint choice model for discrete and continuous housing characteristics a simultaneous discrete and continuous random utility model for housing demand is presented household utility depends on three characteristics of hou sing a discrete number of bedrooms and continuous measures of hous i ng quality and distance to the central business district empirical r esults for a sample of renter households from san francisco are compa red for a univariate structure in which each choice variable has its own utility or disutility function a simultaneous structure assuming a discrete continuous analog of the independence of irrelevant alter natives and one for which this assumption is relaxed the results in dicate that the third structure is most appropriate copyright 1988 by mit press

time varying parameters and the out of sample forecasting performance of structural exchange rate models varying parameter estimation techniques based on recursive application of the kalman filter are used to improve the predictive performance of a class of monetary exchange rate models i find that allowing estimated parameters to vary over time enhances the models forecasting performance for the dollar pound dollar mark and dollar yen exchange rates contrary to earlier results in the literature ex post forecasts for the dollar mark rate compare favorably with those obtained from the naive random walk forecasting rule

cointegration between exchange rates and relative prices another view abstract in this paper the cointegration property of exchange rates and relative prices as implied by the purchasing power parity theory ppp is reexamined using a time varying parameter tvp approach such an approach recognizes the possibility that the lack of cointegration between exchange rates and relative prices found in recent literature may be the result of the nonstationarity of the cointegrating regression parameters themselves the tests of cointegration in a tvp framework indicate that ppp is better supported and point to the presence of structural instability in the long run equilibrium relationship between exchange rates and relative prices

the role of warehouse receipt systems in enhanced commodity marketing and rural livelihoods in africa most african countries have since the 1980s liberalised agriculture without experiencing food crisis as feared by sceptics but the outcome of reforms has been rather disappointing and agricultural markets remain underdeveloped and inefficient one means to improve agricultural marketing which is the focus of this paper is to develop regulated warehouse receipt wr systems the system will curtail cheating on weights and measures ease access to finance at all levels in the marketing chain moderate seasonal price variability and promote instruments to mitigate price risks it will also reduce the need for the government to intervene in agricultural markets and reduce the cost of such interventions if needed the major problem in establishing wr systems in africa is disabling elements in the policy environment drawing on experience from projects implemented in africa during the last decade 1 the authors outline how this challenge can be addressed the most crucial being to build strong stakeholder support behind the initiative 2002 elsevier science ltd all rights reserved

hedging grain price risk in the sadc case studies of malawi and zambia abstract we use simulation methods to examine the results of hedging maize food security imports into malawi and zambia on the south african exchange safex results show that hedging using either futures or options can spread import costs over time thereby reducing variability and also possibly generating lower average costs these benefits are increased if hedging only takes place when local prices are at less than import parity and also if the hedge is levered however problems will remain so long as intra regional transport costs remain high

estimation risk and simple rules for optimal portfolio selection elton gruber and padberg egp 6 7 have recently simplified the process of constructing optimal portfolios by developing simple criteria for optimal portfolio selection which do not involve use of mathematical programming their simple decision rules permit one to determine easily which securities to include in an optimal portfolio and how much to invest in each however in practical applications of theoretical models sample estimators are usually treated as if they were true values of unknown parameters as a result the effect of the standard errors of sample estimators on decision rules are completely ignored bawa brown and klein 1 have shown that what is optimal in the absence of estimation risk is not necessarily optimal or even approximately optimal in the presence of estimation risk moreover brown 4 examined optimal portfolio choice under uncertainty for various portfolio selection procedures the diffuse bayes rule the markowitz certainty equivalent ce rule the aggregation ce rule and the equal weight rule 1 and found that the diffuse bayes rule uniformly dominates the markowitz ce rule in repeated samples for the quadratic utility case as the sample size increases the bayes rule becomes superior to the aggregation ce and the equal weight rules in addition the result holds even where the probability distribution of returns is seriously misspecified thus brown s 4 study has clearly indicated that without taking estimation risk into account portfolio selection rules other than the bayes rule can lead investors to select suboptimal portfolios this paper shows by using the single index model for the return generating process that the simple decision rules for optimal portfolio selection derived by elton gruber and padberg 7 are not identical under the bayesian and the traditional methods of analysis 2 moreover in the case where short sales are not

cointegration how short is the long run abstract when testing for cointegration and faced with short sample periods it is common for researchers to turn to more frequently sampled observations that is to move from annual to quarterly or monthly data in order to increase the number of observations we argue that such a gain in the degrees of freedom is more apparent than real essentially cointegration is a long run concept and hence requires long spans of data to give tests for cointegration much power rather than merely large numbers of observations using monte carlo simulations we demonstrate this for four popular tests for cointegration

generalized optimal hedge ratio estimation a generalized approach to estimating optimal hedge ratios on futures markets is developed the generalized approach is not difficult to apply and provides a framework for evaluating the appropriateness of conventional simple regression approaches to optimal hedge ratio estimation in an application to storage hedging of corn soybeans and wheat it is found that simple regression using price levels or returns leads to errors in optimal hedge ratio estimation but that simple regression using price changes provides reasonably accurate estimates

markov switching garch models for bayesian hedging on energy futures markets abstract effective hedging strategies on oil spot and future markets are relevant in reducing price volatility for investors energy traders and companies operating in the oil markets a new bayesian multi chain markov switching garch model for dynamic hedging in energy futures markets is developed it builds on the construction of a system of simultaneous equations for the return dynamics on the hedged portfolio and the futures the implication of our model for portfolios allocation and energy trading are manyfold first our formulation allows for an easy identification of the different states of the discrete processes as volatility regimes secondly the use of regime switching models with multiple chains allows for an effective way to reduce risk furthermore correlated chains are more flexible than single chain models since they account for co movement in the volatility regimes of different markets thus they should be preferred in turbulent periods e g financial crisis finally the combination of the expected utility framework with the regime switching structure allows us to define a robust minimum variance hedging strategy changes in the optimal hedging strategies before and after the financial crisis are evidenced when the proposed robust hedging strategy is applied to crude oil spot and futures markets it is therefore recommended that many and different models should be used in place of a single one in energy risk hedging since they could perform differently in various phases of the market

the use of organized commodity markets to manage food import price instability and risk the article explores the possibility of insuring the price risks of wheat and maize imports of low income food deficit countries lifdcs optimal strategies for an importing agent who hedges with futures and options are derived based on the objective of minimizing the unpredictability of import bills ex post simulations for a set of lifdcs are run on wheat and maize imports hedged with futures and options in the chicago board of trade to explore the extent to which hedging reduces the unpredictability in import bills simulations encompass both periods of normal price behavior as well as the period of global upheaval that occurred in 2007 and 2008 results show that hedging with futures alone affords agents considerable opportunities for reducing import cost unpredictability and the same holds with options albeit to a lesser extent however during the recent price spike of 2007 2008 hedging with options would have increased the unpredictability of some countries maize import bills due to the combination of erratic import patterns and pronounced market uncertainty

what can we learn from past price stabilization policies and market reform in mexico abstract this paper reviews experience with policy reforms in the maize sector in mexico beginning in the 1980s with particular reference to impacts on price variability it analyses mexico s transition from past price stabilization policies under a state trading enterprise to market reforms implemented during the 1990s the nature extent and costs to producers and consumers of maize policies is discussed for both the pre reform and the reform periods although wide ranging reforms have been introduced impacts on efficiency and fiscal outlays have been less than expected

purchasing power parity and the canadian float in the 1950s in this paper the authors present evidence that neither large differences in inflation nor long time periods are necessary for a finding favorable to purchasing power parity evidence from cointegrating regressions and tests of the real exchange rate indicate that purchasing power parity held as a long run constraint between the united states and canada for the period 1950 10 to 1961 5 the authors also find that government intervention can distort purchasing power parity over a finite period once the data were extended beyond the period of the free float the evidence is no longer favorable to purchasing power parity copyright 1991 by mit press

land allocation under uncertainty for alternative specifications of return distributions using the expected utility moment generating function approach a land allocation rule is derived which is both independent of the nature of the underlying distribution of each element in the choice set and accounts for all moments of that distribution this decision rule is applied to the choice between cotton and corn in the mississippi delta to demonstrate that consideration of just the first two moments of the distribution can often be unjustified and damaging empirically theoretically and in terms of the utility of the decision maker

government spending growth and poverty in rural india using state level data for 1970 93 a simultaneous equation model was developed to estimate the direct and indirect effects of different types of government expenditure on ruralpoverty and productivity growth in india the results show that in order to reduce rural poverty the indian government shoul d give highest priority to additionalinvestments in ruralroads and agricul turalresearch these types of investment not only have much larger poverty impacts per rupee spent than any other government investment but also generate higher productivity growth apart from government spending on education which has the third l argest marginalimpact on ruralpoverty and produc

a reformulation of the portfolio model of hedging the portfolio approach to hedging assumes that the primary motivation for hedging is risk reduction the paper reexamines the portfolio approach to hedging and respecifies the model in such a way that hedge ratios are estimated using returns rather than price levels using the same data set hedge ratios estimated using price levels differ from one while hedge ratios using returns are found to be insignificantly different from one the results do not support the portfolio approach to hedging therefore one must look elsewhere for empirical support for the risk reduction theory of hedging

more reasons why farmers have so little interest in futures markets the use by farmers of futures contracts and other hedging instruments has been observed to be low in many situations and this has sometimes seemed to be considered surprising or even mysterious we propose that it is in fact readily understandable and consistent with rational decision making standard models of the decision about optimal hedging show that it is negatively related to basis risk to quantity risk and to transaction costs farmers who have less uncertainty about prices and those with a diversified portfolio of investments have lower optimal levels of hedging if a farmer has optimistic price expectations relative to the futures market the incentive to hedge can be greatly reduced and finally farmers who have low levels of risk aversion have little to gain from hedging in terms of risk reduction in that the certainty equivalent payoff at their optimal hedge may be little different than the certainty equivalent under zero hedging these reasons are additional to the argument of simmons 2002 who showed that if capital markets are efficient farmers can manage their risk exposure through adjusting their leverage obviating the need for hedging instruments

some recent developments in futures hedging the use of futures contracts as a hedging instrument has been the focus of much research at the theoretical level an optimal hedge strategy is traditionally based on the expected utility maximization paradigm a simplification of this paradigm leads to the minimum variance criterion although this paradigm is quite well accepted alternative approaches have been sought at the empirical level research on futures hedging has benefited from the recent developments in the econometrics literature much research has been done on improving the estimation of the optimal hedge ratio as more is known about the statistical properties of financial time series more sophisticated estimation methods are proposed in this survey we review some recent developments in futures hedging we delineate the theoretical underpinning of various methods and discuss the econometric implementation of the methods

production hedging and speculative decisions with options and futures markets this paper analyzes production hedging and speculative decisions when both futures and options can be used in an expected utility model of price and basis uncertainty when futures and option prices are unbiased optimal hedging requires only futures options are redundant options are used together with futures as speculative tools when market prices are perceived as biased straddles are used to speculate on beliefs about price volatility and to hedge the futures position used to speculate on beliefs about the expected value of the futures price mean variance analysis in general is not consistent with expected utility when options are allowed one extension of sandmo s expected utility model of the competitive firm under price uncertainty considers the use of futures or forward contracts danthine holthausen and feder just and schmitz show that without basis uncertainty the optimal output level is not affected by price risk also with an unbiased futures price the optimal hedging level of the competitive firm is the full hedge while a biased futures price will result in a partly speculative hedge related works include batlin who allows for basis risk in the form of imperfect time hedging paroush and wolf and antonovitz and nelson who consider basis risk with the simultaneous availability of futures and forward contracts grant honda losq newbery and stiglitz and rolfo who allow for production uncertainty chavas and pope who allow for production uncertainty and hedging costs and karp who considers the problem in a dynamic setting this paper provides a further extension of this analysis by allowing options as a means of coping with price risk with the introduction of commodity options on futures for many commodities in the 1980s this problem appears relevant to a number of production settings especially in agriculture specifically this paper considers the simultaneous choice of a production level and of hedging levels of futures and options within the general expected utility model the model allows for basis uncertainty but the production process is assumed to be nonstochastic

purchasing power parity abstract this paper examines the purchasing power parity henceforth ppp using historical data and the cointegration approach the results indicate that the exchange rate is cointegrated with the wholesale price index wpi ratio but not with the consumer price index cpi ratio the cointegrating vector is close to 0 1 for the cpi based real exchange rates however we cannot reject the random walk hypothesis the findings caution us on the use of general price indexes that give a large weight to nontraded goods and are therefore subject to long run deviations from ppp

neighbourhood effects and housing demand in this paper we estimate a model of housing demand with neighborhood eects we exploit special features of the national sample of the american housing survey and properties of housing markets that allow us to create natural instruments and therefore identify the impact of social interactions we find evidence of both endogenous and contextual neighborhood eects we report two alternative sets of estimates for neighborhood eects that dier in terms of the instruments we use for estimating the model when the endogenous neighborhood eect is large the respective contextual eects are weak and vice versa the elasticity of housing demand with respect to the mean of the neighbors housing demands the endogenous eect ranges from 0 19 to 0 66 and is generally very significant the contextual eects are also very significant a key such eect the elasticity with respect to the mean of neighbors permanent incomes ranges from 0 17 to 0 54

hedonic prices demands for urban housing amenities and benefit estimates abstract this paper uses a rosen two step hedonic price trait demand approach to estimate demand functions for a vector of urban amenities to ascertain whether this theoretically preferred approach yields benefit estimates which differ from the oft used ridker henning one step hedonic approach we conduct a sensitivity analysis we find that the two step approach does yield different benefit estimates and that the differences are large for some amenities the estimates are sensitive to the functional form of the hedonic equation when the forms are significantly different according to modified box cox results but are not particularly sensitive to specification of the amenity demand equation

optimal hedging with a subjective view an empirical bayesian approach the standard optimal hedging model has been the preferred theoretical model of normative hedging behavior in empirical applications the model is often implemented with the parameter certainty equivalent pce procedure however the pce procedure completely ignores parameter estimation risk and subjective views we develop an empirical bayesian optimal hedging model that not only effectively accommodates parameter estimation risk but also provides hedgers with a theoretically intuitive yet quantitatively rigorous framework to blend their subjective views and a marketwide or firmwide consensus in determining optimal hedging positions ratios

multiple regime bid rent function estimation abstract this paper reviews estimators for multiple regime selection models which include the standard urban bid rent model as a special case 4 probabilistic bid rent model imposes a restrictive selection process while existing two stage multiple regime estimators assume an error structure that is inconsistent with bid rent theory monte carlo experiments demonstrate that two stage estimators are accurate and robust to distributional misspecification the practical usefulness of the estimators is illustrated using data on 1920s chicago land values

the determination of the real exchange rate the productivity approach abstract this paper explains deviations of exchange rates from purchasing power parity with the differences between countries of the relative growth rates of labor productivity between traded and nontraded sectors two cases are considered germany and japan versus their respective major trading partners the results show that the time series methodology yields a more favorable confirmation of the productivity differential model than the cross section regressions in the literature

regional trade government policy and food security recent evidence from zambia given heavy dependence on rainfed maize production countries in east and southern africa must routinely cope with pronounced production and consumption volatility in their primary food staple typical policy responses include increased food aid flows government commercial imports and stock releases and tight controls on private sector trade this paper examines recent evidence from zambia using a simple economic model to assess the likely impact of maize production shocks on the domestic maize price and on staple food consumption under alternative policy regimes in addition to an array of public policy instruments the analysis evaluates the impact of two key private sector responses in moderating food consumption volatility private cross border maize trade and consumer substitution of an alternate food staple cassava for maize the analysis suggests that given a favorable policy environment private imports and increased cassava consumption together could fill roughly two thirds of the maize consumption shortfall facing vulnerable households during drought years

exploring the logic behind southern africa s food crises summary government action during food crises in southern africa frequently exacerbates the problems driving food staple prices well beyond import parity we argue that an inability to make credible commitments due largely to a lack of trust between public and private sectors contributes to this dynamic empirical policy analysis can facilitate resolution only within a consultative process involving a broad range of stakeholders the policies emerging from such a process are not likely to approximate first best recommendations yet the precise policies may be less important than the fact that they exist and that main stakeholders find them credible

long run purchasing power parity during the recent float abstract this paper examines the relevance of long run purchasing power parity ppp which allows for measurement errors during the recent floating exchange rate period previous empirical studies generally fail to find support for long run ppp over this period in this paper in this paper the cointegration property of exchange rates and prices is examined using maximum likelihood procedure and we find significant evidence favorable to long run ppp further tests for symmetry and proportionality indicate that these two conditions are not generally with the data the results support the hypothesis of long run ppp with measurement errors in prices

a note on simple criteria for optimal portfolio selection using sharpe s 7 single index model elton gruber and padberg egp 4 5 have established some simple ranking criteria for optimal portfolio selection a further extension has been made by chen and brown 2 and alexander and resnick 1 to incorporate the risk associated with the estimation of input parameters this note explores the economic rationale underlying the portfolio formation process based on the single index model in so doing we seek to enhance the intuitive appeal of the simplified portfolio criteria developed in the above studies to practitioners to this end we restate the egp solution with short sales allowed as

differential information and security market equilibrium we propose a simple model of equilibrium asset pricing in which there are differences in the amounts of information available for developing inferences about the returns parame ters of alternative securities in contrast with earlier work we show that parameter uncer tainty or estimation risk can have an effect upon market equilibrium under reasonable conditions securities for which there is relatively little information are shown to have relatively higher systematic risk when that risk is properly measured ceteris paribus the initially very limited model is shown to be robust with respect to relaxation of a number of its principal assumptions we provide theoretical support for the empirical examination of at least three proxies for relative information period of listing number of security returns observations available and divergence of analyst opinion

food price volatility in sub saharan africa has it really increased the food price crisis of 2007 2008 and recent resurgence of food prices have focused increasing attention on the causes and consequences of food price volatility in international food markets and the developing world particularly in sub saharan africa in this paper we examine the patterns and trends in food price volatility using an unusually rich database of african staple food prices we find that international grain prices have become more volatile in recent years 2007 2010 but no evidence that food price volatility has increased in the region this contrasts with the widespread view that food prices have become more volatile in the region since the global food crisis of 2007 2008 in addition the results suggest that price volatility is lower for processed and tradable food than for nontradable food that volatility is lower in the major cities than in secondary cities and that maize price volatility is actually higher in countries with the most active intervention to stabilize maize prices these findings suggest that greater attention should be given to the high level of food prices in the region rather than volatility per se that regional and international trade can play a useful role in reducing food price volatility and that traditional food price stabilization efforts may be counterproductive

the empirical minimum variance hedge decision making under unknown true parameters estimation risk is discussed along with bayes and parameter certainty equivalent pce criteria bayes criterion incorporates estimation risk in a manner consistent with expected utility maximization the pce method which is the most commonly used is not consistent with expected utility maximization bayes criterion is employed to solve for the minimum variance hedge ratio empirical application of bayes minimum variance hedge ratio is addressed and illustrated simulations shoe that discrepancies between prior and sample parameters may lead to substantial differences between bayesian and pce minimum variance hedges

on the deviations from purchasing power parity the case of the ringgit effective exchange rate the paper investigates the extent to which the ringgit exchange rate converges on its purchasing power parity level in the long run using the cointegration and variance ratio tests the results indicate that shifts in the real exchange rate are dominated by permanent stochastic shocks which prevent it from reverting to its ppp base level further analysis indicates that low frequency movements in the relative price of tradable goods and the external terms of trade cannot explain the long run swing in the real exchange rate

the mean and variance of the mean variance decision rule the widely used mean variance approach to decisions under uncertainty requires estimates of the parameters of the joint distribution of returns when optimal behavior is determined using estimates rather than the true values the decision is a random variable we consider the reliability of mean variance analysis by examining the bias and variance covariance matrix for the decision vector the latter shows that decisions based on estimated parameters can have a large variance around the true optimum the results show that optimal decisions can differ substantially from those based on meanvariance analysis

international portfolio diversification with estimation risk international portfolio diversification has long been advocated as a way of enhancing average returns while reducing portfolio risk for the investor who considers diversifying into foreign securities this proposition however relies on the assumption that the required inputs to the classical mean variance analysis are known with certainty typically expected returns variances and covariances are simply replaced by their ex post sample values and the optimal portfolio is derived without mentioning the uncertainty inherent in these parameter values but the rational investor should take this uncertainty into account when forming expectations and probably will consider estimators that are less subject to estimation error than the classical sample mean this paper investigates alternative estimators of expected returns and their implications for the alleged gains from diversification an important observation is the crucial influence that errors in estimating expected returns have on portfolio analysis a closer examiprevious studies of international portfolio diversification have relied on ex post meanvariance analysis without considering the problem of estimation risk typically past averages are substituted for expected returns and no allowance is made for the uncertainty inherent in these parameter values first i demonstrate the shortcomings of such an approach and second i investigate another method of estimating expected returns initially proposed by stein by shrinking the sample averages toward a common mean i find that the out of sample performance of the optimal portfolio is substantially increased one of the implications of this method is that the classical conclusions vastly overestimate the possible gains in average returns instead benefits from diversification are more likely to accrue from a reduction in risk this paper draws on part of my dissertation at the university of chicago i am grateful to arnold zellner michael mussa george constantinides and especially john bilson for useful discussions and comments numerous improvements were also suggested by the referee this research received the generous financial support of the college interuniversitaire d etudes doctorales dans les sciences du management

efficient estimation methods for closed ended contingent valuation surveys closed ended contingent valuation surveys can be very useful in the evaluation of nonmarket resources respondents merely state whether they would accept or reject a hypothetical threshold amount either as payment for giving up access to the resource or as a fee for its use the authors develop a maximum likelihood procedure which exploits the variation in the threshold values to allow direct and separate point estimates of regression like slope coefficients and error standard deviations without truncation bias their illustration uses data from a survey of recreational fisherman to examine factors which influence individuals willingness to pay copyright 1987 by mit press

an empirical investigation into the performance of ellickson s random bidding model with an application to air quality valuation abstract this paper compares ellickson s random bidding model to the standard hedonic model in estimating benefits due to marginal and non marginal changes in housing attributes using data on the chicago housing market the paper shows that the benefit estimates obtained using the two models are very close in addition various categorizations based on household characteristics are tested in the case of the random bidding model the study shows that the effect of categorization on the overall benefit estimates are negligible moreover the results from the random bidding model reveal that increased income leads to greater demand for environmental quality

land use worker heterogeneity and welfare benefits of public goods we show that investments in public goods change the optimal land use in their vicinity leading to additional welfare benefits this occurs through two sorting mechanisms first availability of public goods leads to higher population densities second population groups sort according to their preferences for public goods we develop a structural spatial general equilibrium model that accounts for these effects the model is estimated using data on transport infrastructure commuting behaviour land use and land rents for some 3000 zip codes in the netherlands and for three levels of education welfare benefits of investments in public transport infrastructure are shown to differ sharply by workers educational attainment welfare gains from changes in land use account for up to 30 of the total benefits of a transport investment

a simple multiperiod minimum risk hedge model a multiperiod hedging model is developed that is simpler than other multiperiod models in the literature the model permits periodic adjustment of the hedge while minimizing the producer s profit variance minimum risk hedge ratios are calculated for steers cows hogs corn and soybeans using the full model with hedge adjustments every two months these ratios are compared to those using the model without periodic hedge adjustments and to a simple single period model the results suggest that simple models may work well for simple hedges while the full model is best for more complex hedging situations such as cross hedges our purpose in this paper is to develop a multiperiod hedging model in which the hedge can be updated each period other multiperiod hedging models e g anderson and danthine karp have substantial data requirements which limit their use as viable hedging tools our aim is to develop a simpler model that will have practical application the model is used to calculate minimum risk hedge ratios for steers cows hogs corn and soybeans and these ratios are compared with hedge ratios based on a multiperiod model in which the hedge cannot be adjusted each period simple minimum risk hedge ratios also are computed for each commodity and compared with the other ratios

is there trend reversion in purchasing power parity abstract this study presents some empirical evidence on purchasing power parity ppp using residualbased co integration tests engle and granger s 1987 tests and the ratio of the variance of higher order differences to the variance of the first difference of the residuals of the cointegrating regression are used monthly data over a span of 30 years do not provide any empirical support to the theory conversely in the annual data long run equilibrium tendencies are evident since ppp has been widely used to provide an anchor for the equilibrium exchange rate our results indicate that such an assumption is not completely inadequate