This thesis has been approved by:

Over the last few months, I have received a lot of help and support by many people whom I would like to thank here. I would like to start by thanking my supervisors Ivan and Lúıs. They have been a source of inspiration for me throughout the process of the research and writing. Their feedback and insights were always valuable, and never went unused. Writing a paper with them was a new experience, but they were patient with me. Related to this, I would like to thank Marcel van Amstel. Without his knowledge on metrics, my performance measures would have been just numbers. Special thanks go to Klaas van den Berg. Although not directly involved in this graduation project, he did supervise my research that was the basis of it. My roommates at the fifth floor at Zilverling provided a great working environment. I thank them for the laughs and talks we had. Not all was work during the past few months. Therefore, I would like to thank my friends at ZPV-Piranha for the diving trips we made together, both in the murky waters in The Netherlands and in the deep blue seas around Curaçao. Of course, this acknowledgment would complete without thanking my par-ents. Having supported me throughout my university, I cannot express my gratitude enough. My girlfriend Renske more than deserves to be named here too. Throughout the process of my graduation research, she has been loving and supportive