Secular stagnation? Is there statistical evidence of an unprecedented, systematic decline in growth?

So far it is difficult to establish firm evidence that the recent decline in growth is indeed systematic, unprecedented, and significant. In order to provide more statistical evidence of a decline in economic growth, we use a data-driven nonparametric estimation approach which improves boundary estimators, using an extended iterative plug-in (IPI) algorithm to determine the bandwidth endogenously. We identify continuously Moving Trends (MT) with a length of 18 years for US GDP. Two introduced tests demonstrate a persistent decline in US trends and growth rates since the dot.com bubble. Hence, the 2008 financial crisis merely revealed that GDP, labor, and multi-factor productivity trends were already stagnating. (C) 2019 Elsevier B.V. All rights reserved.