A Joint Algorithm of SBM-DDF and Global Malmquist Luenberger Index for Green Total Factor Productivity of Urban Industry Based on Matlab

The Pearl River Delta region(PRD) is one of the most open-minded and active regional economic centers in mainland China, and also has an important position in the world economic map. This paper incorporates energy inputs and unexpected outputs into the analytical framework of total factor productivity, constructs the SBM-DDF model, and collects balanced panel annual data from 2010-2019 for nine cities in the PRD region, and measures the SBM-based efficiency values. It was found that the industrial green total factor productivity in the PRD showed a sharp decline and a rapid rise similar to a large “V” pattern. From the city’s perspective, the industrial green total factor productivity in Zhaoqing, Zhuhai, Zhongshan, Jiangmen, and Shenzhen was higher, while that in Dongguan, Huizhou, Foshan, and Guangzhou was lower. Based on the SBM efficiency value, the GML index was calculated and decomposed into technical efficiency progress and technical progress. It is found that the change of GML index reflecting green total factor productivity is mainly driven by technological progress, which reveals that science and technology is the most important driver of total factor productivity improvement, and it is essential to take the path of scientific and technological innovation for high-quality economic development.