In the context of international financial crises, what mathematical methods have Economists employed in order to quantify financial contagion?
Note: For a working definition of contagion I'll use the description supplied by Kaminsky, Reinhart & Vegh (2003):
We refer to contagion as an episode in which there are significant immediate effects in a number of countries following an event that is, when the consequences are fast and furious and evolve over a matter of hours or days. This fast and furious reaction is a contrast to cases in which the initial international reaction to the news is muted.