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I would like to thank Prof. Ekkehard Sachs, my supervisor, for his many suggestions and constant support during this research. I am also thankful to Prof. John A. Burns for making a special trip to Trier to serve as examiner. During work on this thesis I was employed as a research associate for Prof. Dieter Sad-owski in the Dept. of Economics at the University of Trier. A special measure of gratitude is due Prof. Sadowski for providing ample research time and moral encouragement. On a related note, I wish to thank my colleagues at the University of Trier and the Institute for Labor Law and Labor Relations (IAAEG), especially Dipl.-Vw. Tanja Machalet and Anne Besslich, for maintaining a friendly working environment. I am deeply indebted to my wife, Petra, and our children, Helena, Michael, Matthew and Hannah for their patience and support during the many long hours I spent working on this thesis. Finally, I wish to thank Dipl.-Wirtsch.-Math. Bärbel Bender, who read through th