Consumption externalities,market imperfections and optimal taxation

In a dynamic model with a keeping‐up‐with‐the Joneses preference and market imperfections, we attempt to investigate under what circumstances and for what reason the optimal tax should be state‐varying. We extend the Ljungqvist and Uhlig (2000) proposition to include preferences that exhibit non‐homotheticity. We show that a keeping‐up‐with‐the‐Joneses preference (a non‐intertemporally‐dependent preference) can lead the social planner to commit to a state‐contingent tax on labor income. Moreover, the optimal labor income tax can be either procyclical or countercyclical with respect to economic fluctuations, this crucially depending on whether the level of contemporaneous consumption increases or decreases the wedge between the intertemporal substitution elasticity of households and of the social planner.     

Interest rate option pricing with volatility humps

This paper develops a simple model for pricing interest rate options when the volatility structure of forward rates is humped. Analytical solutions are developed for European claims and efficient algorithms exist for pricing American options. The interest rate claims are priced in the Heath-Jarrow-Morton paradigm, and hence incorporate full information on the term structure. The structure of volatilities is captured without using time varying parameters. As a result, the volatility structure is stationary. It is not possible to have all the above properties hold in a Heath Jarrow Morton model with a single state variable. It is shown that the full dynamics of the term structure is captured by a three state Markovian system. Caplet data is used to establish that the volatility hump is an important feature to capture. This revised version was published online in June 2006 with corrections to the Cover Date.     

Stackelberg thresholds in network routing games or the value of altruism

It is well known that the Nash equilibrium in network routing games can have strictly higher cost than the optimum cost. In Stackelberg routing games, where a fraction of flow is centrally-controlled, a natural problem is to route the centrally-controlled flow such that the overall cost of the resulting equilibrium is minimized.We consider the scenario where the network administrator wants to know the minimum amount of centrally-controlled flow such that the cost of the resulting equilibrium solution is strictly less than the cost of the Nash equilibrium. We call this threshold the Stackelberg threshold and prove that for networks of parallel links with linear latency functions, it is equal to the minimum of the Nash flows on links carrying more optimum flow than Nash flow.Our approach also provides a simpler proof of characterization of the minimum fraction that must be centrally controlled to induce the optimum solution.     

空间双寡头竞争下的创新扩散——基于博弈论的模型

关于创新空间扩散的研究一直没有关注空间竞争对于创新采纳的影响.本文在双人博弈的框架下构建了一个空间双寡头竞争模型,假定厂商已经拥有关于创新的信息,单纯地考察空间竞争对于创新采纳的影响.结果表明,即使同质的厂商同时获得了创新的信息,在竞争的作用下,创新的采纳很少会同时进行.先采纳者具有先发优势,且随着运费率的下降,先发优势愈发得以强化.本文还分析了空间竞争和技术扩散反梯度现象间的关系,结论是空间竞争至少是反梯度现象产生的一个原因.     

从多哈回合中止看多边贸易谈判机制的效率

本文主要探讨了多边贸易谈判机制存在的必要性、经济学本质,及其顺利运行的前提条件。     

Pediatric gastroesophageal reflux disease and acid-related conditions: trends in incidence of diagnosis and acid suppression therapy

Abstract

Objective: To describe the incidence of diagnosis of gastroesophageal reflux disease and acid-related conditions (GERD/ARC) throughout childhood and characterize patterns of diagnosis and treatment with proton pump inhibitors (PPIs) and histamine-2 receptor antagonists (H₂RAs).

Methods: Cohorts of GERD/ARC children (age 0–18 years) were identified from a large US administrative claims database covering 1999–2005 using ICD-9 codes. Incidence, healthcare utilization (HCU), costs, therapy discontinuation and switching rates were compared between various age and patient groups.

Results: Between 2000 and 2005 annual incidence of GERD/ARC diagnosis among infants (age ≤1 year) more than tripled (from 3.4 to 12.3%) and increased by 30% to 50% in other age groups. Patients diagnosed by GI specialists (9.2%) were more likely to be treated with PPIs compared to patients diagnosed by primary care physician (PCP). PPI-initiated patients doubled (from 31.5% in 1999 to 62.6% in 2005) and, when compared with H₂RA-initiated patients, were associated with 30% less discontinuation and 90% less therapy switching in the first month, and with higher comorbidity burden and pre-treatment total HCU and costs when diagnosed by GI specialists.

Limitations: The use of an exploratory definition for GERD/ARC, administrative claims data and potential coding errors in diagnosis codes used in selection process may limit the generalizability of the results.

Conclusions: GERD/ARC incidence increased for children of all ages between 2000 and 2005. PCPs made the majority of diagnoses. PPI initiations have now surpassed H₂RA initiations.     

Fees for Reefs: Economic Instruments to Protect Mexico’s Marine Natural Areas

Stated preference methods can be used to estimate the demand function where no price variation has been observed before. This is the situation of the Mexican coral reef natural protected areas, where after the 2002 approval of a $20 pesos fee (US$1.80) the Ministry of the Environment is now considering increasing the amount of the fee, not only to raise more revenue for the park, but also to curb the number of visitors in the cases where there is excess demand. There are concerns that the very success of the reefs is bringing associated environmental damage that threatens its sustainable use. To estimate the reaction of visitors to different fee levels, we carried out a contingent valuation survey, and constructed with its results an aggregate demand for each park. This demand was then divided by seasons and nationalities, to explore the benefits and costs of differentiating fees, looking at both the revenue maximising and the welfare maximising fees. Finally we discuss how these fees would change when environmental damage functions are taken into account. The recommendation is that increasing fees up to the point where they cover both private and environmental costs would bring the highest amount of economic benefit compatible with the sustainable use of these complex and wondrous marine ecosystems.     

Anglo versus Hispanic Children's Influence on Parental Purchase of Cereal

Children's influence on parental purchases of cereal was investigated by unobtrusively observing 15 pair of Anglo and 15 pair of Hispanic children and their parent(s) in the cereal aisle of Allentown, Pennsylvania grocery stores. Tabulation was kept on whether the child did or did not influence the purchase behavior of their parent(s). It was found that overall, children had a statistically significant influence on their parents' purchase behavior (p < .01). Although a percentage difference existed, there was no statistically significant difference between the Anglo children's influence and the Hispanic children's influence on their parents' purchasing behavior of cereal (p < .05).     

Measurement of Milk Container Preferences

Consumer preference for container types for fluid milk was investigated for gallon and half gallon containers using conjoint analyis. Consumers clearly preferred plastic jugs to paperboard for gallon containers, which explains the nearly complete capture of the gallon milk market by plastic. They prefer paperboard for half gallon containers, which corresponds to the failure of plastic to penetrate that size container very well. Relative prices of container types are adjusted for the utility consumers see in the containers. Utility adjusted prices of plastic gallon containers make them very competitive relative to alternative packaging materials. Prices of plastic half gallon containers make them less competitive once utilities are accounted for.     

水电施工企业的索赔管理

水电施工企业在工程建设中加强成本控制、加强索赔管理、提高索赔意识，对水电工程合同管理具有重要意义。文章对如何加强水电施工企业的索赔管理进行了论述。