AN APPLICATION AND EXTENSION OF THE MARKOV CHAIN MODEL TO CEREAL PRODUCTION

Given aggregate time-series data, conventional Markov Chain estimation of the stationary transition probabilities is performed for a model of the cereal market in Great Britain. The possibility of non-stationary probabilities is examined in the light of these initial results, and the basic model developed to allow exogenous variables to enter via their influence on these parameters. The evidence from the paper would appear to suggest that, at least in the case considered, time-varying transition probabilities are a most attractive alternative.     

Eliciting farmers’ subjective probabilities,risk, and uncertainty preferences using contextualized field experiments

Subjective probabilities as well as risk and uncertainty preferences influence many farmers’ decisions. Few contextualized field experiments were recently conducted to elicit farmers’ risk preferences. Contextualized field experiments use nonabstract framings that are familiar to subjects. Despite adding of context can undermine internal validity, such experiments are increasingly used in applied economics. Contextualized field experiments were never used to elicit farmers’ uncertainty preferences. This paper aims to fill this gap in the literature. This required the development of a new approach in which uncertainty preferences were estimated while controlling for farmers’ subjective probabilities regarding future agricultural outcomes. The experiment involves Scottish farmers’ decisions to plant traditional or new potato varieties. Monetary incentives and incentive compatible elicitation techniques, such as quadratic scoring rules and certainty equivalent multiple price lists, were used. Results from the estimation of Fechner models using maximum likelihood estimation procedures show that failure to control for subjective probabilities generates an underestimation of estimated uncertainty preferences. Farmers are more averse to uncertainty than risk, and their choices are noisier under uncertainty than risk.     

闽东粮食产量气象风险评估与分析

加强粮食气象灾害风险的分析和评估工作,对农业种植结构调整、防灾减灾和可持续发展具有重要意义。文章采用1949~2013年闽东9县市区粮食产量资料,应用线性拟合方法计算出粮食气象产量增长率时间序列作为分析对象,通过经验正交分解(EOF)、线性倾向估计、概率分布函数拟合及检验、聚类分析等气候统计学方法,分析闽东粮食气象产量增长率空间与时间变化特点,减产率等级分布特征及风险区划。结果表明,闽东山区粮食增长率总体要高过沿海县市,增产趋势更明显些。粮食增长率的空间特征值与年平均气温、日照时数为显著负相关,山区与沿海的气候差异与粮食增长率密切相关。9县市粮食增长率具有斜"L"型年际变化特征,可分为下降、上升、缓降、持平等4个阶段。聚类分析表明闽东粮食具有显著增产、一般增产、一般减产和显著减产等4类年型,增产与减产年份发生概率分别为54.3%、45.7%。沿海县市轻、中度减产发生概率要大于山区县,而重度减产发生概率则相反,山区县减产风险普遍高于沿海县市区。闽东总体增产年份比减产年份略多,但减产年份发生概率也较大,农业气象灾害造成减产危害不可忽视,因此加强粮食生产的农业气象防灾减灾工作十分重要。     

Estimating Policy Effects on Spatial Market Eff iciency: An Extension to the Parity Bounds Model

The standard parity bounds model (PBM) is extended to allow for dynamic shifts in regime probabilities in response to changes in marketing policy. The approach allows estimation of the length of the adjustment period and a statistical test for no policy effects. The extended PBM is applied to maize and wheat markets in Ethiopia. Evidence of a dynamic adjustment path is found and grain marketing reforms are found to have improved spatial efficiency in a few markets, worsened it in a few others, but generally to have had little effect on the spatial efficiency of Ethiopian grain markets.     

EXPECTED VALUES OF COSTS AND REVENUES DEPENDENT ON DROUGHT†

In earlier papers on drought, sequences of wet and dry months were treated as realisations of binomial trials with periodic probabilities of failure (dry months), and the cost-revenue outcomes of alternative drought strategies were handled probabilistically. When costs and revenues may be represented by a set of second degree polynomials over a set of adjacent subranges of the time scale, their expectation may be expressed as a simple closed formula in the twelve probabilities of dry months. As an illustration of the use of these new formulae, means and standard deviations of drought duration calculated in this manner are presented for three typical localities in Queensland. Previously known closed formulae for the mean and the variance in the case where all calendar months have equal probability of being dry emerge as special cases and are verified.     

Exporting to new destinations and the effects of tariffs: the case of meat commodities

This study uses a random parameter probit estimation to examine the effects of tariff liberalization on the probability of establishing new trading relationships in meat commodities. Our simulation results indicate that the effects of tariff reductions decrease with distance, but increase with the level of development. The probabilities of trade increase at an increasing rate with the size of tariff reductions thus justifying calls for ambitious liberalization schemes. Canada and Mexico are the NAFTA countries that are most likely to export in response to EU tariff reductions on bovine and poultry meats, while Brazil and Argentina emerge as the MERCOSUR countries most likely to penetrate the EU bovine meat market after EU tariff reductions. Uruguay's probability to export poultry meat is most responsive to EU tariff reductions.     

Food consumption dynamics: a nonparametric approach using maximum entropy estimation

We model dynamic consumer choice in a stochastic optimal control framework and show conditions under which observable market share data possess the Markov property. Using 30 years of annual aggregate milk consumption data differentiated by fat content, maximum entropy is used to estimate nonstationary transition probabilities showing how consumer tastes and preferences have changed over time. The maximum entropy approach allows for the estimation of a 4 × 4 transition probability matrix for each year of the sample. Results suggest that skim milk was an absorbing state over most of the sample but that the trend toward skim milk has decelerated and possibly reversed itself since 1998. Our approach provides a useful complement to existing parametric approaches to demand analysis when data are limited or the problem is ill‐posed.     

AGRICULTURAL EXPORTS OF DEVELOPING COUNTRIES: ESTIMATES OF INCOME AND PRICE ELASTICITIES OF DEMAND AND SUPPLY

This paper provides new evidence on income and price elasticities of demand and supply of agricultural exports from developing countries, on the basis of (a) a consistent and fully specified supply and demand model, and (b) statistical estimation procedures not frequently used in the estimation of agricultural export functions. Estimates of price and income elasticities of demand for aggregate agricultural exports for all developing countries taken together — as distinct from individual exporting countries — are found to be low; moreover, export price as distinguished from non-price factors plays a relatively insignificant role in increasing export supply. Hence, an attempt by all developing countries to expand traditional agricultural exports with low price elasticity of demand may not yield rising earnings for all; but in fact may result in falling export revenues. Insofar as individual exports of all developing countries (not individual countries) are concerned, income and price elasticities of demand for such tropical commodities as tea, coffee, cocoa and bananas are also found to be low, except for new, non-traditional exports like pineapples. This indicates the importance of diversification of agricultural exports as a vehicle for their future growth.     

Distinguishing between Equilibrium and Integration in Spatial Price Analysis

This article introduces a new spatial price analysis methodology based on maximum likelihood estimation of a mixture distribution model incorporating price, transfer cost, and trade flow data. This method permits differentiation between market integration and competitive market equilibrium and derivation of intuitive measures of intermarket tradability, competitive market equilibrium, perfect integration, segmented equilibrium, and segmented disequilibrium. One can also use these estimates to derive semiparametric measures of time-varying regime probabilities to track changing market conditions. An application to trade in soybean meal among Pacific Rim economies demonstrates the usefulness of the method.     

ESTIMATION OF EFFECTIVE RISK REDUCION THROUGH IRRIGATION OF A PERENIAL CROP*

This paper outlines an approach to assessing the benefits from in vestment in the irrigation of tea stands in three areas of East Pakistan. Irrigation aflects both the establishment and productive life of the growing crop, and therefore the analysis includes a discounred assessment of the replacement decision, as well as an appraisal of the change in technology. Since the biological and weather eflects that determine annual and long-run productivity of the stand are stochastic variables, the evaluation is made using a simulation model in which these determinants are introduced as known discrete probabilities. Using this model an estimate may be made of rhe net gains to a tea estate of the risk reduction achieved by eliminating harmful crop moisture deficits.     

Is Risk Aversion Really Correlated with Wealth? How Estimated Probabilities Introduce Spurious Correlation

Economists frequently focus on correlations between wealth and risk preferences but rarely observe the probabilities needed to test this relationship empirically. These unobserved probabilities are typically estimated via profit or production functions conditioned on wealth correlates, which may leave statistical fingerprints on subsequently-estimated risk aversion coefficients and confound correlations between wealth and risk preferences. Using data from an experiment with observable probabilities, we compare risk aversion coefficients based on true probabilities with those based on probabilities estimated using standard approaches and show how estimated probabilities can change risk aversion coefficients substantially and introduce spurious correlation between risk aversion and wealth.     

A COMPARISON OF TOBIT AND OLS ESTIMATES OF JAPANESE PEANUT IMPORT DEMAND

A Tobit analysis is applied to estimate Japanese peanut imports under quota restrictions for the period 1973–1988, and to assess the bias when the presence of quota is ignored by using OLS estimation. The results show that biased estimates are obtained by using OLS in the presence of quota restrictions.     

A FORECAST OF MILK SUPPLY IN ENGLAND AND WALES

This paper reports the problems encountered in applying Markov Chain analysis to the Permanent sample of milk producers in England and Wales, and presents predictions obtained for producer numbers and milk output, by regions, for the years 1970/71 and 1975/76. As a consequence of the “pool of entrants” problem, dificulties arise both in estimating the required transition probabilities and in forecasting producer numbers. Solutions to these, and to other problems concerned with obtaining prediction of milk output, from those of producer numbers, are proposed. It is forecast that producer numbers will decline by 18 per cent and 33 per cent by 1970/71 and 1975/76 respectively, with the largest proportional decline occurring among smaller producers. Two forecasts are made of milk supply and these are compared with estimates made by the Milk Morltetiiic Board.     

CHANCE AND CHOICE WEST OF THE DARLING

Twenty-one pastoralists in the West Darling region of New South Wales were interviewed to gain an understanding of the attitudes of managers in this high-risk pastoral area to uncertain prospects. It was found that pastoralists had no difficulty in specifying subjective probabilities but in modifying probabilistic information they were conservative relative to the 'correct' revision implied by Bayes' Theorem. All the surveyed pastoralists were non-indifferent to risk, as evidenced by their non-linear utility functions for gains and losses.     

ESTIMATION OF A PRODUCTION FRONTIER MODEL: WITH APPLICATION TO THE PASTORAL ZONE OF EASTERN AUSTRALIA

This paper considers a statistical model for a production frontier that is consistent with the traditional (nonstochastic) definition of a production function given in microeconomic theory. Limiting cases of the model are the familiar average production function and an envelope production function. Maximum-likelihood estimators for the parameters of the model are defined. The three related models are applied in the estimation of a production frontier for the Pastoral Zone of Eastern Australia with use of data from the Australian Grazing Industry Survey.     

物理模型光谱模拟误差对冬小麦叶面积指数高光谱反演的影响

获取农作物叶面积指数(leaf area index,LAI)及其动态变化对于农作物长势监测和产量估测等应用具有重要的意义。基于冠层反射率模型(物理模型)的LAI遥感反演方法具有良好的普适性,对地面数据依赖较少,近年来广泛应用于农作物LAI高光谱反演研究。然而,当物理模型参数取值尽可能准确(代入参数实测值或依据先验知识取值)时,模拟光谱与实测光谱间仍然存在误差,研究称之为"光谱模拟误差"。该研究通过比对实测冬小麦冠层光谱与ACRM(a two-layer canopy reflectance model)模型最优模拟光谱,展示了光谱模拟误差在各波段、不同样本点的分布规律。据此,根据对光谱模拟误差与高光谱数据降维的不同考虑,制订了4种LAI反演波段选择方案。通过对比基于不同波段选择方案的LAI反演精度,分析了光谱模拟误差对LAI反演的影响;讨论了综合考虑高光谱数据降维与光谱模拟误差的LAI反演波段选择方法。通过合理的波段选择,限制了光谱模拟误差的影响,提高了LAI反演精度。该研究结果有助于探索合理的LAI高光谱反演波段选择方法,为合理利用高光谱数据反演农作物LAI提供科学参考。     

A MULTIVARIATE PROBIT ANALYSIS OF ADVERTISING AWARENESS ON MILK USE

In this study an attempt was made to determine and evaluate the factors affecting an individua?s probability of milk use in terms of a multivariate probit model. Cross-sectional survey data obtained through telephone interviews of individuals in three New York State Markets were used in the analysis. Various economic, demographic and socio-economic variables were hypothesized as being influential in determining an individual's likelihood of using fluid milk. Accordingly, the respondent's age was found to be highly influential in determining probability of milk use. Specifically, milk use probabilities were found to decrease as the age of the respondent increased. Moreover, the probability of milk use was found to be significantly greater for male respondents than for females. Also, if an individual was a consumer of beer or coffee, his probability of milk use was significantly reduced. Milk use probabilities were also reduced if the respondent was a consumer of soft drinks; however, they increased if he was a consumer of fruit juices or drinks. The level of household income was not found to be significant in affecting the respondent's probability of milk use. In general, if an individual could recognize the milk promotion theme and identify it with milk, his likelihood of milk use was greater than for his peer who was unaware of the promotion theme.     

PRODUCTION RISK AND INPUT USE: PASTORAL ZONE OF EASTERN AUSTRALIA

Few attempts have been made to estimate production functions for the Australian grazing industries. The question of the nature of the effect of input levels on production risk has been broached even more rarely. Previous investigators had to employ models and methods of estimation which embody highly restrictive implicit assumptions about the nature of risk effects. A typical restrictive feature has been the implication that increasing input intensity leads to increasing risk. In this paper, a much less restrictive model and corresponding estimation techniques are brought to bear on individual farm data for 38 properties with 10 continuous years of production records. Perhaps not surprisingly, it is found that some inputs (especially those capital inputs which might normally be thought of as increasing the safety of production) tend to reduce risk.     

A MICRO-ECONOMIC APPROACH TO THE ANALYSIS OF SUPPLY RESPONSE IN BRITISH AGRICULTURE

Most of the work undertaken on the estimation of supply response in U. K. agriculture has been based on the analysis of time-series data. However, there are a number of problems associated with an analysis of aggregate supply response for British agriculture based on time-series analysis alone. This paper reports on an alternative supply response model being developed at Newcastle in which estimates of aggregate supply levels are built up from optimal programmes for a set of representative farms.     

FUTURES PRICES AS FORECASTS OF COMMODITY SPOT PRICES: LIVE CATTLE AND WOOL*

In this paper the foundations on which the predictive interpretation of futures prices rests are discussed, and possible reasons for the differential predictive performance of futures prices as between different commodity markets examined. The predictive performances of futures, and spot prices themselves, are tested empirically, using Australian data for wool (a continuous inventory commodity) and finished live beef cattle (virtually a non-storable commodity), by means of instrumental variables estimation.