临沂市需水预测信息系统的研究和探讨

借鉴国内外节水管理的成功经验,结合临沂市具体情况,建立了临沂市需水预测模型,并在此基础上把数据库技术和需水预测模型进行系统集成,研究和探讨了临沂市需水预测信息系统的开发,并建立了完整的系统数据库.该系统将为临沂市今后的经济发展模式选择和水利工程建设提供可靠依据.     

A Note on Estimating Nested Constant Elasticity of Substitution Preferences for Outdoor Recreation

A generalized version of a well-known statistical result is used to suggest an alternative strategy for estimating nested constant elasticity of substitution preferences for recreation demand. Parameter and welfare estimates from nested constant elasticity of substitution count data demand system models are presented and compared to estimates from the multinomial approaches developed previously. A significant advantage of the count data estimation strategy over the multinomial-based approaches is that the analyst avoids the difficulties associated with choice occasion specification and interpretation.     

Demand for maize hybrids and hybrid change on smallholder farms in Kenya

Kenya is a globally recognized maize “success story.” As the overall percentage of maize farmers growing hybrids tops 80% and the seed industry matures, the slow pace of hybrid replacement on farms, and the continued dominance of the seed industry by Kenya Seed Company, may dampen productivity. Our econometric analysis identifies the factors that explain farmer demand for hybrid seed, and the age of hybrids they grow, considering hybrid seed ownership. Male‐headed households with more education, more assets, and more land plant more hybrid seed. Scale of seed demand per farm is differentiated by agroecology. We find a strong farmer response to the seed‐to‐grain price ratio, which we interpret as evidence of a commercial orientation even on household farms. However, despite the dramatic increase in the number of hybrids sold and the breadth of seed suppliers as seed markets liberalize, an older hybrid still dominates national demand.     

Promotion and Fast Food Demand

Many believe that fast food promotion is a significant cause of the obesity epidemic in North America. Industry members argue that promotion only reallocates brand shares and does not increase overall demand. We study the effect of fast food promotion on market share and total demand by estimating a discrete / continuous model of fast food restaurant choice and food expenditure that explicitly accounts for both spatial and temporal determinants of demand. Estimates are obtained using a unique panel of Canadian fast food consumers. The results show that promotion primarily increases demand and has a smaller effect on restaurant market shares.     

Deriving a Flexible Mixed Demand System: The Normalized Quadratic Model

This article deals with the specification of a locally flexible and theory-consistent system of mixed demand functions, a framework that allows for a rich set of possibilities about what is assumed as exogenous in a demand model. A coherent mixed demand system is derived by using the restricted expenditure function typically studied in the related area of rationed demands. The method is implemented by a new normalized quadratic (NQ) parameterization of the restricted expenditure function. The resulting NQ mixed demand system is illustrated with an application to a nine-good model of the Italian demand for vegetables.     

Efficient Estimation of Hedonic Inverse Input Demand Systems

This article is concerned with efficient estimation of characteristics demand. We derive and estimate an inverse input demand system for quality characteristics by using 172,946 observations over 881 trading days in the Icelandic fish auctions. An improved estimation method based on an expanded random coefficient model is suggested as an alternative to the currently used two-stage method of Brown and Rosen . The estimates demonstrate the improved efficiency of the suggested method. A number of empirical results emerge, including a general increase in the demand for quality.     

生态建设与消费产品贸易市场一体化的探讨

消费需求是生产建设的动力和目的,决定生态建设过程、设计、经营管理方式和人文社会背景特征:生态建设是以需求为核心的复杂动态、过程和系统。消费需求动态发生变化,整个生态建设的复杂系统也随之发生变化。消费产品贸易市场一体化改变贸易的数量、方式、成本、速度、场所、规则等,进而改变生态建设产品消费的数量、内容、特征等消费需求动态和时空演变规律。市场一体化通过改变需求动态对生态建设产生全方位的深刻影响。     

Capturing structural changes in French meat and fish demand over the period 1991 2002

A time-varying coefficient demand system, the Markov switchingalmost ideal demand model, is proposed to shed new light onchange over time in the structure of French meat and fish demand.The main feature of this model is that the switching mechanismfrom one structure of demand to the other is controlled by anunobserved variable that follows a Markov chain. Our model accuratelycaptures the two Bovine Spongiform Encephalopathy (BSE) crisesof recent years. We estimate that the 1996 BSE crisis lastedalmost three years, whereas the second BSE crisis for just lastedfive 4-week periods.     

An Error Corrected Almost Ideal Demand System for Crustaceans in the United States

We have employed an error-corrected almost ideal demand system (ECAIDS) for major crustaceans at a disaggregated level in the United States. The proposed model can provide short- and long-run price elasticities. This article makes an important empirical contribution by reporting a set of reliable, policy-relevant estimates of the elasticities of demand for crustaceans in the United States. The habit formation behavior was significant only for crayfish. The value pricing strategy and the promotional pricing strategy are expected to benefit the domestic shrimp industry. Increasing prices through various marketing strategies can benefit domestic producers of lobsters and crabs.     

The Nested PIGLOG Model: An Application to U.S. Food Demand

A new demand system is introduced, the Nested PIGLOG model, nesting thirteen other demand systems including five that are also new. This new model and its nested special cases are applied to models of U.S. food demand that include food-at-home (FAH), food-away-from-home (FAFH), and alcoholic beverages. Although nested tests and out-of-sample forecasting performance favor generalizing models to a certain degree, statistically insignificant improvements to in-sample-fit and even poorer out-of-sample forecast accuracy undermine further generalizations. Based on a subset of preferred models, FAFH is found to be price and income elastic compared to FAH which is price and income inelastic.     

Food Demand in Mexico: An Application of the Amemiya-Tobin Approach to the Estimation of a Censored Food System

The modeling of micro-level food demand patterns requires not only allowing for household heterogeneity, but also addressing the problem of censoring. In this article, we present a variation of the Amemiya-Tobin framework for estimating a censored demand system that allows for household heterogeneity. The unique aspect of our approach is the use of a procedure that ensures the adding up of both latent and observed expenditure shares and also imposes expenditure share nonnegativity. This system is applied to an analysis of food demand based on a random sample of urban Mexican households.     

Have health claims affected demand for fats and meats in Canada?

Chronic illness is a global epidemic and places significant economic and social burdens on societies. Research has shown that a healthy diet can be used to mitigate or significantly reduce the risk of many chronic illnesses. Health authorities around the world have begun regulating health claims on foods to encourage the consumption of healthy foods. However, the “ex post” efficacy of health claims regulations on consumers demand for healthy foods has not been assessed. The demand for fats and meats in Canada is estimated using a linear-approximate almost ideal demand system. The results indicate health claims decreased unhealthy food demand between 1.41% and 7.10% and increased healthy food demand between 1.95% and 8.50%.     

A new market for an old food: the U.S. demand for olive oil

While U.S. consumption of olive oil has tripled over the past two decades, nearly all olive oil continues to be imported. Estimation of a demand system using monthly import data reveals that the income elasticity for virgin oils sourced from EU is above one, but demand for nonvirgin oils is income‐inelastic. The demand for olive oil as a single product is price‐inelastic. Differentiated by product characteristic and origin, olive oils are highly substitutable with each other but not with other vegetable oils. News about the health and culinary benefits of olive oil and the spread of Mediterranean diet contribute significantly to the rising demand.     

正确认识我国林业基本矛盾 加速商品林业发展

通过对我国社会的基本矛盾及其运动和表现方式在林业中的体现分析 ,可以得出 ,供需矛盾是现阶段我国林业的主要矛盾。而有效需求单一和不足则是林业矛盾的主要方面。在市场经济条件下 ,大力发展商品林业是扩大林业有效需求的重要手段     

家庭禀赋对农户公益林收益权质押贷款需求影响研究

基于浙江省丽水市调查数据,采用Logistic模型和Tobit模型,实证分析家庭禀赋对农户公益林收益权质押贷款需求及其额度的影响。结果表明:大多数农户对贷款有需求;农户存在以中长期生产性借贷为主的潜在贷款需求特征;家庭的人力资本、社会资本、自然资本、经济资本均是影响农户公益林收益权质押贷款需求的因素;公益林大户相对于公益林小户贷款需求意向更为强烈;家中发生大事、政府贴息、贷款期限、林权抵押贷款经历均对农户公益林收益权质押贷款需求和需求额度具有显著正向影响;贷款用途限制对农户公益林收益权质押贷款需求和需求额度具有显著负向影响。因此,政府机构应鼓励各地加大贴息力度,为农户提供融资增信,银行业金融机构应合理确定贷款期限,农户应注重自身资源禀赋的积累和利用,政府及各地基层、相关金融机构应加大金融宣传力度。     

Using Elasticities from an Almost Ideal Demand System? Watch Out for Group Expenditure!

Group expenditure has often been treated as exogenous when estimating demand parameters for a group of commodities with an almost ideal demand system. Researchers draw demand elasticities from past literature to use in their own analysis, but elasticities contingent on exogenous group expenditure may be inappropriate. Here, the approach is considered in the case of Japanese meat demand with a simple equation added to estimate group expenditures. The results show that elasticities should be revised and that a group expenditure equation is not a panacea as it may result in the violation of theoretical restrictions, such as symmetry.     

A Meta‐Analysis on the Elasticity of Demand for Pesticides

There is an increasing policy interest in pesticide taxation schemes as a measure to reduce harmful effects of pesticide use. The effectiveness of such tax depends, however, on the price elasticity of demand for pesticides. Moreover, information on these demand elasticities and their determinants is of crucial relevance for policy‐making and normative modeling approaches. In this article, we present a meta‐analysis based on studies that have estimated pesticide demand elasticities in Europe and North America. Our meta‐analysis reveals that the own‐price elasticities of demand for pesticides are, with a median of ?0.28, significantly smaller than zero, but also significantly larger than ?1, i.e. to be inelastic. We find that the demand for pesticides for special crops is less elastic than that for arable and grassland. In addition, the demand for herbicides is more elastic than for other pesticides. Studies that consider only short‐term horizons and little flexibility for farmers to adjust to price changes generate significantly less elastic pesticide demands. The results also indicate that more recent studies identify lower pesticide price elasticities of demand. Furthermore, we find that peer‐reviewed studies tend to find more inelastic results compared to grey literature.     

The Demand for Organic and Conventional Produce in London,UK: A System Approach

The majority of studies on consumer demand for organic products neglect the presence of non‐organic competitors, ignoring their effect on consumer demand for organics. This article uses a demand system which includes both organic and non‐organic fruits and vegetables, with actual (as opposed to stated) data for household purchases. Estimation of our model provides empirical evidence on the interrelationships between organic and non‐organic products, as the relevant cross‐price elasticities. Own‐price elasticities indicate that organic fruits and vegetables are more price elastic than their non‐organic counterparts, and that lower social class households with children have the most own‐price elastic demand. Cross‐price elasticities indicate relatively strong loyalty to organic products.     

An econometric analysis of demand for food quantity and quality in urban China

This article offers an analytical framework for studying consumer demand for food quality based on a theory‐consistent demand model, namely, the Exact Affine Stone Index specification. Importantly, it accounts for unobserved consumer and regional heterogeneity, and allows for arbitrary Engel curves. The empirical value of our framework is illustrated in an econometric analysis of demand for food quality in China. Evaluating possible structural changes in consumer food expenditures in China is of paramount importance, given the ever‐increasing global role of China and the implications of the structural food preference changes for the global food system. The major findings emerging from this study indicate that income is an important determinant of demand for food quality and quantity with the relatively more affluent provinces having a higher affinity for food quality.     

Wholesale Demand for Fish in Greece

Inverse demand systems explain price variations as functions of quantity variations. This article presents a dynamic inverse almost ideal demand system (AIDS) model based on recent developments on cointegration techniques and error correction model. The case of fish landed at Greek seaports appears to suit this model well. The results indicate that the underlying distance function is homothetic whereas the own-quantity flexibilities suggest that the responses of price to own-quantity changes are inelastic. Finally, the results of cross-quantity uncompensated flexibilities suggest that the substitution possibilities among fish grades are rather limited. The Allais interaction intensities verified the substitutability among fish grades as well.