In more general settings, such as the one analyzed by Gali (1992)
and Wickens and Motta (2001), where there are m endogenous variables and r long-run or cointegrating relations, the SVAR approach provides m(m − r) restrictions which are
not sufficient to fully identify the model, unless m = 2 and r = 1 which is the simple
bivariate model considered by Blanchard and Quah. (Pagan and Pesaran, 2006). In most
applications additional short term restrictions are required. More recently, attempts have
also been made to identify structural shocks by means of qualitative restrictions, such as
sign restrictions. Notable examples include Canova and de Nicolo (2002), Uhlig (2005)
and Peersman (2005).