“…In the international business cycle literature, for example, global technology shocks -widely assumed the primary force driving world business cycles -are typically viewed as persistent but stationary (see, e.g., Kehoe and Perri, 2002); the same applies to global demand (spending) shocks (e.g., Boileau et al, 2010). In other situations, it may be more difficult to rule out common stochastic trends; for example, panel tests of purchasing power parity usually involve country-specific I(1) variables defined relative to a reference country, and this tends to introduce common stochastic trends in the analysis (e.g., Urbain and Westerlund, 2011).…”