3.3.3. Panel Tobit Model

Because the patent quantity and quality data were non-negative, and had the characteristics of truncated data [37], this study used the panel Tobit model to estimate, and the results are shown in Table 8. The results show that the coefficients of sub on the quantity of technological innovation were all significantly positive, and the coefficients on the quality of technological innovation were still not significant, which is consistent with the benchmark regression results.


**Table 8.** Robustness test: Panel Tobit model.

Note: z-statistics are given in parentheses. \* *p* < 0.1, \*\* *p* < 0.05, \*\*\* *p* < 0.01. CONTROLS includes capital structure (*lev*), profitability (*roa*), enterprise size (*size*), proportion of fixed assets (*ppe*), proportion of independent directors (*dir*), enterprise age (*age*), enterprise growth ability (*gov*), and human capital (*hc*).

## 3.3.4. System-GMM Model

Considering that the level of technological innovation in the previous period may have an impact on the level of technological innovation in the current period, this paper introduced the independent variable lagging behind the first phase and used the system-GMM model to estimate. As shown in Table 9, it was found that the quantity and quality of technological innovation in the previous period had a significant positive impact on the quantity and quality of technological innovation in the current period. The government subsidies had a significant positive impact on the quantity of technological innovation, but had no significant impact on the quality of technological innovation, which is consistent with the benchmark regression results.


**Table 9.** Robustness test: System-GMM model.

Note: z-statistics are given in parentheses. \* *p* < 0.1, \*\* *p* < 0.05, \*\*\* *p* < 0.01. CONTROLS includes capital structure (*lev*), profitability (*roa*), enterprise size (*size*), proportion of fixed assets (*ppe*), proportion of independent directors (*dir*), enterprise age (*age*), enterprise growth ability (*gov*), and human capital (*hc*).
