Robust min–max portfolio strategies for rival forecast and risk scenarios

We consider an extension of the Markowitz mean–variance optimization framework to multiple return and risk scenarios. It is well known that asset return forecasts and risk estimates are inherently inaccurate. The method proposed provides a means for considering rival representations of the future. The optimal portfolio is computed, simultaneously with the worst case, to take account of all rival scenarios. This is a min-max strategy which is essentially equivalent to a robust pooling of the scenarios. Robustness is ensured by the noninferiority of min–max. For example, a basic worst-case optimal return is guaranteed in view of multiple return scenarios. If robustness happens to have too high a cost, guided by the min–max pooling, it is also possible to explore other pooling alternatives. A min–max algorithm is used to solve the problem and illustrate the robust character of min–max with return and risk scenarios. We study the properties of the min–max risk–return frontier and compare with the potentially suboptimal worst-case where the investment strategy and the worst case are computed separately.     

Discrimination by shipping conferences?

Shipping conferences have for years been under heavy attacks from developing countries. It was with a view to finding out whether there was any justification for these grievances that the HWWA-Institut für Wirtschaftsforschung — Hamburg (The Hamburg Institute for International Economics) prepared a wide-ranging inquiry for the Federal Ministry of Transport, the most important results of which are summarised in the following article.     

The Operating Performance of Newly Privatised Firms in Central European Transition Economies

This study examines the operating performance of privatised firms in three Central European Transition Economies between 1990 and 1998. Overall, we find no evidence of a significant improvement in operating performance for the first six years after privatisation. Contrary to the increasing empirical evidence for non‐transition economies, our privatised firms experience no improvement in profitability, capital investments, efficiency, and output, a significant drop in employment, as well as a significant increase in leverage. The most important determinants of the performance changes following privatisation were country effects, timing of the privatisation sales, industry classification, and state ownership after privatisation. Our findings are consistent with the empirical evidence that the transition process proved to be more difficult than expected and that, although necessary, privatisations do not necessarily produce equal efficiency gains in transition economies ( Megginson, 2005 ; Havrylyshyn and McGettigan, 1999 ).     

How useful is the concept of the natural real rate of interest for monetary policy?

The natural rate of interest plays a key role in Wicksell's‘cumulative process’ as well as in modern monetaryequilibrium models of the business cycle. It constitutes a usefulconcept for the theoretical analysis of the interdependenceof monetary policy and economic fluctuations. However, the usefulnessof this concept for the practice of monetary policy is limited—especiallyowing to the fact that the natural real rate of interest andits law of motion cannot be measured with satisfying precision.     

Covered interest parity in non-dollar euromarkets

Zusammenfassung Gedeckte Zinsparit?t auf Nicht-Dollar-Eurom?rkten. —- In diesem Aufsatz werden die Beziehungen zwischen Zinss?tzen und Wechselkursen auf den Eurom?rkten für andere W?hrungen als den U.S.-Dollar untersucht. Dabei zeigt sich, da\ Heteroskedastizit?t ein wichtiges Problem in den Daten ist. Tests, die mit der Heteroskedastizit?t konsistent sind, werden unter Benutzung der Korrektur nach White durchgeführt. Aus diesen Tests ergibt sich, da\ die These von der gedeckten Zinsparit?t abgelehnt werden k?nnte. Doch liegen die beobachteten Abweichungen von der gedeckten Zinsparit?t innerhalb der Grenzen, die sich aus den Transaktionskosten ergeben.

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Résumé Parité d’intérêt couverte en euro-marchés non-dollar. — Les auteurs examinent les relations entre des taux d’intérêt et des taux de change en euro-marchés non-dollar. Ils trouvent que la hétéroscédasticité est un problème significatif regardant les données. Des tests hétéroscédasticité-consistants sont conduits en utilisant la correction de White. Ces tests démontrent que la parité d’intérêt couverte (PIC) pourrait être refusée. Cependant, les auteurs trouvent que les déviations de la PIC observées sont dans des limites déterminées par les frais de transaction.

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Resumen La paridad de tipos de interés con seguro de cambio en los Euromercados alternativos al del dólar. — Se examinan las relaciones entre los tipos de interés y los tipos de cambio en los Euromercados alternativos al del dólar. La muestra presenta problemas de heteroscedasticidad. Se llevan a cabo tests consistentes con la heteroscedasticidad utilizando la corrección de White. Estos tests demuestran que la paridad de tipos de interés con seguro de cambio podría ser rechazada. Las deviaciones observadas, empero, permanecen dentro de los límites impuestos por los costos de transacción.

     

Little Firms and Big Patents: A Model of Small‐Firm Patent Signaling

Patent strategies of small technology‐intensive firms are difficult to explain with standard incentive arguments based on intellectual property rights. This paper develops a rationale for patent filing as a disclosure strategy. We develop a two‐sender signaling game to study patenting incentives of two technology start‐ups to file in a large‐scale patent system with the goal to attract a user firm. Both start‐ups may decide to invest in costly modification of their patent application before filing. The paper identifies a separating equilibrium in which the high‐quality inventor files and so separates from its technology competitor. Of particular interest is the study of pooling and semi‐separating equilibria, as well as the impact of subsidies. We find that a higher quality of a country's inventions, reflected in the possible innovative steps and thus in higher expected profits for foreign user firms, may increase the chance of the relatively lower‐quality inventor to enter international technology markets.     

Labour‐market institutions and their impact on trade partners: A quantitative analysis

Recent theoretical literature studies how labour market reforms in one country can affect labour market outcomes in other countries, thereby rationalizing widely held policy beliefs and empirical evidence. But what is the quantitative relevance of such spillover effects? This paper combines two recent workhorse models: the canonical search‐and‐matching framework and the heterogeneous firms international trade model. Qualitatively, the framework confirms that labour market reforms in one country benefit its trading partners, replicating the stylized facts. However, when wages are bargained flexibly, the model quantitatively underestimates the correlation of structural unemployment rates across countries. Introducing some degree of real wage rigidity remedies this problem.     

Consumer Affairs in Rural New Zealand

Recent changes in many areas of Government policy as well as changes in the private sector have had major impacts on the provision of services in rural areas of New Zealand. This report describes the results of a New Zealand survey of 795 rural consumers. The results emphasise how the problems perceived as most important to people in rural areas are essentially linked to fundamental services such as housing, water, communications, and transport. Though this element of basic needs is covered in the consumer policy literature it is not a feature that tends to be emphasised. The survey also gauges some aspects of rural consumers' knowledge of their entitlements under New Zealand consumer law and their familiarity with, and use of, consumer advisory and support services.