The Uncertain Unit Root in U.S. Real GDP: Evidence with Restricted and Unrestricted Structural Change.

In this article the researchers use Lumsdaine and Papell tests for a unit root in the presence of unrestricted structural change and Papell and Prodan test for a unit root in the presence of restricted structural change to study the long-term real gross domestic product (GDP) in the U.S. The unit root null is rejected at the 1% level with both tests. Using the Murray and Nelson method to evaluate the rejections, the researchers discover that, unlike the Augmented-Dickey-Fuller (ADF) tests, the unit root null is not rejected too often if the data generating process is a unit root with transitory fluctuations.