A test for a regime shift
This note describes a formal statistical approach to testing for a regime shift based on population time series for a system of interacting species or groups. Under this approach, a regime shift is said to occur if the system switches abruptly from varying around one locally stable steady state to varying around another. This allows the problem to be formulated as testing for a changepoint in a vector autoregressive process. The test is illustrated using data from the North Sea covering the period 1963–97.