Conditionally heteroscedastic unobserved component models and their reduced form

The reduced form of the local level model with conditionally heteroscedastic GARCH(1,1) noises is analyzed. We show that the IMA-GARCH model is a good alternative but its conditional heteroscedasticity is weaker than this of the unobserved disturbances.     

Impact factor as a metric to assess journals where OM research is published

This paper investigates impact factor as a metric for ranking the quality of journal outlets for operations management (OM) research. We review all prior studies that assessed journal outlets for OM research and compare all previous OM journal quality rankings to rankings based on impact factors. We find that rankings based on impact factors that use data from different time periods are highly correlated and provide similar rankings of journals using either two-year or five-year assessment periods, either with or without self-citations. However, some individual journals have large rank changes using different impact factor specifications. We also find that OM journal rankings based on impact factors are only moderately correlated with journal quality rankings previously determined using other methods, and the agreement among these other methods in ranking the quality of OM journals is relatively modest. Thus, impact factor rankings alone are not a replacement for the assessment methods used in previous studies, but rather they evaluate OM journals from another perspective.     

Economic analysis of different options in integrated pest and soil fertility management in maize systems of Western Kenya

The major biotic constraints to the production of maize, the major staple food in Western Kenya, are field pests such as Striga and stem borers, and low soil fertility. To counter these constraints, new cropping systems have been developed, including “push‐pull,” rotations with promiscuous soybean varieties and green manure crops, and imidazolinone resistant‐ (IR‐) maize. To analyze the technical and economic performance of these technologies, both with and without fertilizer, on‐farm researcher‐managed long‐term trials were implemented over six seasons in two sites each in Vihiga and Siaya districts of Western Kenya. The economic results, based on marginal analysis using a multioutput, multiperiod model, show that the new cropping systems with fodder intercropping (push‐pull) or soybean rotations were highly profitable. Push‐pull is more profitable but requires a relatively high initial investment cost. Green manure rotation, IR‐maize, and fertilizer all increased yields, but these investments were generally not justified by their increased revenue. We argue that research on rotation and cropping systems to tackle pest and soil fertility problems in Africa deserve more attention. This will require increased collaboration between agronomists and economists to set up long‐term experiments with new cropping systems to develop proper economic models.     

刍议跨国并购交易中的几个关注因素

在全球经历了五次并购浪潮后，越来越多的中国公司希望通过跨国并购的形式寻求海外投资机会，实现跨越式发展。有鉴于此．中华咨询与美国波士顿商学院联合进行了跨国并购领域的专项研究，     

Estimating GARCH volatility in the presence of outliers

GARCH volatilities depend on the unconditional variance, which is a non-linear function of the parameters. Consequently, they can have larger biases than estimated parameters. Using robust methods to estimate both parameters and volatilities is shown to outperform Maximum Likelihood procedures.     

Effects of Prominence,Involvement, and Persuasion Knowledge on Children's Cognitive and Affective Responses to Advergames

The integrated and highly involving nature of advergames has led to criticism and concern among academics and caretakers. It is assumed that children are highly susceptible to persuasion via advergames, but empirical evidence is scarce. Therefore, this study examined the effects of three factors typically associated with advergames: brand prominence, game involvement, and (limited) persuasion knowledge on cognitive and affective responses. An experiment among 7 to 12 year old children (N = 105) showed that brand prominence and game involvement influenced children's responses, while persuasion knowledge did not. Brand prominence led to increased brand recall and recognition, whereas game involvement led to more positive brand attitudes. The effect of game involvement was mediated by game attitude, indicating that children are susceptible to affective mechanisms induced by the game. Crucially, our results demonstrate that brand prominence evokes cognitive responses, while game involvement leads to affective responses. Finally, our study revealed that persuasion knowledge (i.e. knowledge of the commercial source of the game and its persuasive intent) did not influence cognitive or affective responses to the brand or game. This implies that even if children understand the game's commercial and persuasive nature, they do not use this knowledge as a defense against the advergame's effects. This study has important theoretical and practical implications regarding the influence of new marketing techniques on children.     

Grandmothers and Granddaughters: Old-Age Pensions and Intrahousehold Allocation in South Africa

This article evaluates the impact of a large cash transfer programin South Africa on children's nutritional status and investigateswhether the gender of the recipient affects that impact. Inthe early 1990s the benefits and coverage of the South Africansocial pension program were expanded for the black population.In 1993 the benefits were about twice the median per capitaincome in rural areas. More than a quarter of black South Africanchildren under age five live with a pension recipient. Estimatessuggest that pensions received by women had a large impact onthe anthropometric status (weight for height and height forage) of girls but little effect on that of boys. No similareffect is found for pensions received by men. This suggeststhat the efficiency of public transfer programs may depend onthe gender of the recipient.     

Minimum Differentiation in Commercial Media Markets

We examine a model of locational choice in commercial media markets. Commercial media (stations) compete for audiences with their choice of programming variety in order to attract advertising revenues from advertisers. These advertisers (producers) compete in a differentiated product market and rely on advertising to inform consumers about their product. We use the model to show that media have incentives to minimize the extent of differentiation between them. This incentive is an implication of the assumed role of advertising as information and as an ultimate nuisance to the audience. When stations minimally differentiate their programming offerings, producers choose lower levels of advertising. Consequently, lower levels of product information are available to consumers, permitting producers to gain higher margins on product sales. As a result, stations can negotiate higher payments for advertising space.