Diverging European sovereign bond yields after 2008 are the most visible sign of the European debt crisis. This dissertation examines in a first step, to which extent the development of yields is driven by credit and liquidity risk, and how it is influenced by general uncertainty on financial markets. It can be shown that yields are driven to a significant degree by a flight towards bonds of high liquidity in times of high market uncertainty. In a second step, high yields are interpreted as a sign of an existing crisis in the respective country. Using the signals approach, the early-warning capabilities of four different proposals for the design of the scoreboard as part of the 'Macroeconomic Imbalances Procedure' (introduced in December 2011 by the European Commission) are tested, advocating a scoreboard including a variety of many different indicators. In a third step, the methodology of the signals approach is extended to include also results on significance.