Convergence analysis of eco-efficiency of China's cement manufacturers through unit root test of panel data

China has become the largest producer and consumer of cement worldwide. In 2011, carbon emissions of China's cement industries accounted for 60.6% of cement carbon emissions worldwide. In this context, this paper mainly investigates whether eco-efficiency of China's cement manufacturers has converging tendency or not. First, we evaluated eco-efficiency under directional distance function (DDF) and the directional slack-based measure (DSBM) to compare their biases. Furthermore, we also implement unit root test of panel data to testify convergence analysis upon eco-efficiency in different regions of China in order to overcoming the demerit of conventional convergence approach, which might have invalid inferences. Our empirical analysis revealed that eco-efficiency under DDF has gaps with that under DSBM due to excess input or output shortages. Eco-efficiency in the east, middle and west converged. It is necessary to substitute raw material, increase additive and improve waste use for China's cement manufacturers. (C) 2017 Elsevier Ltd. All rights reserved.