We use the well known USDA dataset of real exchange rates to address the question of whether PPP holds for agricultural commodities. Both unit root tests and the recently proposed more powerful class of panel unit root tests, which take into account cross-section correlation across the units in the panel, are used. Properties of unit roots and panel tests are analyzed by Monte Carlo simulation....

Note The purpose of this series of studies is to analyse policy issues and to stimulate discussions in the area of international trade and development. The series includes studies by UNCTAD staff and by distinguished researchers from other organizations and academia. This paper represents the personal views of the author only, and not the views of the UNCTAD secretariat or its member States. Th...

INTRODUCTION World trade in agricultural commodities continues to grow. As agricultural trade expands, it increases the risk of introducing exotic insects into new areas where they may become plant pests. The establishment of new pests can be costly due to increased crop damage, control programs, and quarantine restrictions on trade. Quarantine or phytosanitary treatments such as cold, fumigati...

Auf den wirtschaftlichen Erfolg der Stadtwerke München haben Energiepreise einen großen Einfluss. Ändert sich jedoch nur ein Parameter, beispielsweise der Ölpreis, kann dies Auswirkungen auf die Preise anderer Commodities haben. Die Stadtwerke München nutzen daher eine Vielzahl miteinander verketteter Marktmodelle. Mit dem weltweiten Gasmarktmodell WEGA können Gaspreise errechnet und beispielsw...

The prevalence of reciprocal cooperation in non-human animals is hotly debated [1, 2]. Part of this dispute rests on the assumption that reciprocity means paying like with like [3]. However, exchanges between social partners may involve different commodities and services. Hitherto, there is no experimental evidence that animals other than primates exchange different commodities among conspecifi...