Clients play an important role in projects because they are the ones for whom a project is usually intended and made use of. They determine project scope, influence project implementation and test a project's result (Project Management Institute, 2004). Consequently, meeting their needs is an important criterion for achieving project success (Turner, 1999; Takim, 2009). However, project managers report that it is hard to satisfy their client's needs, especially when projects are complex and face high levels of uncertainty (Boehm