To Reviewer # 3: Thank you for your careful reading and thoughtful reviews

T o Reviewer #3: Thank you for your careful reading and thoughtful reviews. Q1: Theorems 3 and 4. (i) Theorem 3: Theorem 3 shows that SD2 helps to reduce the overestimation bias compared We empirically show that SD2 does not underestimate and can reduce the absolute bias in Figure 4. The left-hand side in Eq. (19) equals to Q5: How is the performance of the proposed approximation method? We will try to further investigate it in future research. Q2: Related works about ensemble methods.