## 3 Materials and Methods
### Empirical Model
#### 3.3.3 Control Variables  
However, the satisfaction of farmers with GPPs is influenced not only by policy structure and policy implementation, but also by individual, family, and production characteristics, among others [22]. To more accurately explore the impacts of policy structure and implementation on farmers' satisfaction with GPPs, and to avoid model estimation bias caused by missing variables [41], a series of control variables were added, including individual, family, and production characteristics [42; 43; 44]. Individual characteristics included gender, age, health condition, and education. Family characteristics included the labor force, production specialization, and village cadres. Production characteristics included cooperation, training, and demonstration. The definitions and descriptive statistics of the variables are listed in Table 1.  
Figure 4: Farmers’ evaluations of the implementation effects of agricultural GPPs. Figure 3: Farmers’ evaluations of different agricultural GPPs. cial, technical, subsidy, and supervision policies had significant impacts on the satisfaction of farmers with GPPs, and the degree of impact varied. Further analysis revealed that service, financial, and subsidy policies were all statistically significant at the 1% level, while technical and supervision policies were statistically significant at the 10% and 5% levels, respectively. The coefficients of all policy structural variables were positive, indicating that the implementation of these agricultural policies can improve farmers' satisfaction with GPPs, but there were differences in their marginal benefits. Specifically, the marginal utility of agricultural service policies on farmers' satisfaction with GPPs was the highest at 40.7%. The second- and third-highest were those of financial insurance and subsidy policies, which were 33.6% and 30.4%, respectively. The marginal utilities of technical guidance and production supervision policies were the lowest at 12.8% and 11.0%, respectively. The research findings were consistent with those of previous studies [22], which suggested that regulation has a significant impact on agricultural policy satisfaction. These findings validated research hypothesis 1. The results of Models (2) and (3) indicated that policy implementation significantly affected farmers' satisfaction with GPP, and the conclusion remained stable after adding control variables. From the perspective of policy implementation evaluation, the support intensity, degree of promotion, policy sustainability, and implementation effect all had significant impacts on farmers' satisfaction with GPPs, and the degree of impact varied. Further analysis revealed that the evaluations of the support intensity and implementation effect were statistically significant at the 1% level, while those of the degree of promotion and policy sustainability were statistically significant at the 5% and 10% levels, respectively. The coefficients of all policy implementation variables were positive, indicating that a positive evaluation of these aspects of policies can improve the satisfaction of farmers with GPPs, but there were differences in their marginal benefits. Specifically, the positive evaluation of the policy implementation effect had the highest marginal utility on farmers' satisfaction with GPPs, reaching 63.6%. Second, the evaluation of the policy support intensity and degree of promotion were respectively 11.1% and 10.54%, while the evaluation of policy sustainability had the lowest marginal utility, at only 3.29%. Based on the preceding theoretical analysis, this indicated that policy implementation improves farmers' satisfaction with GPPs, thus verifying Hypothesis 2. In terms of the control variables, previous conclusions were further confirmed [9; 32]. Specifically, among individual characteristics, the age and health condition variables were statistically significant at the 1% level, indicating that both the age and health condition of farmers can significantly affect their satisfaction with GPPs.