“…However, this method is only applicable to multi-input and single unit output (Wang et al, 2018;Wang & Cai, 2020). The nonparametric method refers to data envelopment analysis (DEA), which solves the problem of multi-input and multi-output by constructing the traditional DEA model (Andriamasy et al, 2014;Sun, 2020). Many scholars combine the DEA model with the Malmquist index to analyze the changing trends in technological innovation efficiency from the static and dynamic perspectives, respectively (Luo et al, 2019;Wang et al, 2019a;Liu et al, 2019;Sue & Ma, 2018).…”