The importance of consumer multihoming (joint purchases) for market performance: Mergers and entry in media markets

Consumer “multihoming” (watching two TV channels, or buying two news magazines) has surprisingly important effects on market equilibrium and performance in (two‐sided) media markets. We show this by introducing consumer multihoming and advertising finance into the classic circle model of product differentiation. When consumers multihome (attend more than one platform), media platforms can charge only incremental value prices to advertisers. Entry or merger leaves consumer prices unchanged under consumer multihoming, but leaves advertiser prices unchanged under single‐homing: Multihoming flips the side of the market on which platforms compete. In contrast to standard circle results, equilibrium product variety can be insufficient under multihoming.     

Periodic strategies in optimal execution with multiplicative price impact

We study the optimal execution problem with multiplicative price impact in algorithmic trading, when an agent holds an initial position of shares of a financial asset. The interselling decision times are modeled by the arrival times of a Poisson process. The criterion to be optimized consists in maximizing the expected net present value of the gains of the agent, and it is proved that an optimal strategy has a barrier form, depending only on the number of shares left and the level of the asset price.     

对群众体育锻炼中，如何合理安排运动量的探讨

本文在体育锻炼能够增强体质，提高健康水平的生物学基础上和群众体育锻炼与专业训练的区别上，提出群众体育锻炼中如何合理安排运动量。     

Optimal Emissions Taxation under Imperfect Competition in a Durable Good Industry

This paper investigates optimal emissions taxation under imperfect competition in a durable good industry where products are sold (instead of rented). As a benchmark, attention is paid to the special case of monopoly with exogenously given product durability. In line with previous literature, the optimal emission tax in this benchmark model falls short of marginal damage (underinternalization). Extending the benchmark model either to the case of an oligopolistic market structure and/or to the case of endogenous product durability then provides two cases in which the optimal emission tax overinternalizes marginal damage.     

American-style Indexed Executive Stock Options

This paper develops a new pricing model for American-style indexed executive stock options. We rely on a basic model framework and an indexation scheme first proposed by Johnson and Tian (2000a) in their analysis of European-style indexed options. Our derivation of the valuation formula represents an instructive example of the usefulness of the change-of-numeraire technique. In the paper's numerical section we implement the valuation formula and demonstrate that not only may the early exercise premium be significant but also that the delta of the American-style option is typically much larger than the delta of the otherwise identical (value-matched) European-style option. Vega is higher for indexed options than for conventional options but largely independent of whether the options are European- or American-style. This has important implications for the design of executive compensation contracts. We finally extend the analysis to cover the case where the option contracts are subject to delayed vesting. We show that for realistic parameter values, delayed vesting leads only to a moderate reduction in the value of the American-style indexed executive stock option.     

Designing Optimal Crop Revenue Insurance

When the indemnity schedule is contingent on the farmer's price and individual yield, an optimal crop revenue insurance contract depends only on the farmer's gross revenue. However, this design is not efficient if, as is the case with available contracts, the coverage function is based on imperfect estimators of individual yield and/or price. The producer's degree of prudence and the extent of basis risks have important influences on the optimal indemnity schedule. In this broader context, optimal protection is not provided by available U.S. crop insurance contracts and may include combinations of revenue insurance, yield insurance, futures, and options contracts.     

Tinbergen in De Economist

Jan Tinbergen's scientific writings cover six main areas of research. His articles in De Economist represent these areas; in some cases the contributions to De Economist were of a pioneering nature (business cycles, economic models, economic integration); in others De Economist was the first or even single outlet for Tinbergen's work. This article provides an overview of these contributions. The wide scope of Tinbergen's areas of research goes together with a unity in approach, the characteristics of which are: policy relevance, quantification and measurement, balance in analysis and presentation, and learning from experience. Tinbergen's articles in De Economist bear witness to this approach which at the time also met with scepticism and resistance as this overview shows. According to Houthakker, Tinbergen's main contribution may be that, amidst the pleas of interest groups and the slogans of the laity, an attempt is made that the voice of the professional economic researcher be heard. Tinbergen's work still sets an agenda for both economic research and policy making.     

Discussion and Analysis about Duration Method Based on Marginal Analysis

The selective principle of mutually exclusive project is the maximum of net present value, It is difficult to make decision when NPVA is equal to NPVLB. Some assistant analyses are put forward in ＂Enterprise Investment Decision Management＂. The scientific marginal analysis shows that the assistant analyses including the duration analysis are wrong. This problem can be solved by the classical marginal analysis.     

浅论乒乓球运动对全民健身的影响及作用

随着社会的不断发展和进步,人民生活水平的日益提高,健康已成为众人的追求目标。在不断增加的健身运动中,不受条件限制,运动量相对适中,又有娱乐性质的乒乓球运动逐渐被更多的人接受并喜爱。本文从运动生理学、人体解剖学的角度出发,从理论上阐述和剖析乒乓球运动的健身价值。