Several people played an important role in the course of this thesis to who I am thankful. First I have to thank Rita Coelho do Vale, my supervisor, whose wisdom, expertise, and guidance were essential for the course of this work. Her clear vision, intellectual rigor, and permanent support were decisive for the completion of this thesis. I also thank my teachers in ISEG that opened my eyes for the importance of Marketing. I am also grateful to my family. My parents, for always encouraging me, for their support and for teaching me to be autonomous and responsible. My mother for being such an example and my father from whom I learned the taste to travel and explore new worlds. I also thank my sisters, Joana for showing me how interesting this...