Jansson, Michael; Nielsen, Morten Ørregaard - School of Economics and Management, University of Aarhus - 2009
In an important generalization of zero frequency autoregressive unit root tests, Hylleberg, Engle, Granger, and Yoo (1990) developed regression-based tests for unit roots at the seasonal frequencies in quarterly time series. We develop likelihood ratio tests for seasonal unit roots and show that...