“…Under most circumstances, the ceilings and floors are reached with two absolute reduction policies, (0, 1, −1) and (−1, 1, −1), respectively. However, for Ningxia, Shandong and Jiangsu, relative reduction policy (−1, 1, 0) results in the highest values of local MAC, indicating that the arbitrariness of direction choice might have big impacts on the estimated shadow price and implied cost-effectiveness of agricultural GHG reduction (Vardanyan and Noh, 2006; Ma et al. , 2019).…”