In 2014, the Beijing-Tianjin-Hebei Collaborative Development Strategy (hereinafter the Jing-Jin-Ji Strategy) was formally proposed as a major national strategy, providing an unprecedented opportunity for the overall development of Hebei. This article evaluates the treatment effects of the Jing-Jin-Ji Strategy on Hebei's economy and environment. Employing a panel data program evaluation method developed by Hsiao et al. (2012), we construct hypothetical counterfactuals for the GDP growth rate, the percentage of tertiary industry in GDP, and the geographic mean PM2.5 concentrations for Hebei in the absence of the Jing-Jin-Ji Strategy using the outcomes of selected untreated provinces. The results show that the Jing-Jin-Ji Strategy increased the percentage of tertiary industry in GDP by an average of 2.53 percentage points per year between 2014 and 2018 and decreased the geographic mean PM2.5 concentrations by an average of 11.1 percentage points per year between 2014 and 2017. However, it does not appear to have had significant effects on Hebei's GDP growth rate. The leave-one-out method demonstrates the robustness of the above results. This article suggests that Hebei should speed up its economic growth and bridge the gap with Beijing and Tianjin while ensuring the quality of its economic development and a sound ecological environment.
Keywords: Beijing-Tianjin-Hebei Collaborative Development Strategy; Counterfactual analysis; Panel data approach; Treatment effects.