Tests for Nonlinearity in EMS Exchange Rates

This paper tests for nonlinearity in EMS exchange rates using the bispectrum. The early experience of the ERM witnessed numerous realignments. We find that exchange rates follow a linear process over the period 1979-1987, consistent with the predictions of the realignment target zone model, where a stabilizing nonlinearity is absent. But from 1987-1992, no realignments occurred, and many currencies conformed to a nonlinear process, consistent with the credible target zone model where an inherent nonlinearity stabilizes exchange rates. However, the Italian lira and the Irish pound follow a linear process, which suggests that a target zone has not proven effective in stabilizing exchange rates.