ABSTRACT The computable general equilibrium (CGE) model is often used to analyse the effects of policy changes because of its ability to capture multi-sectoral inter-linkages within the economy. The results of a CGE analysis largely depend on the database, policy shock and elasticities. Trade elasticities, such as the Armington elasticities, play a central role in CGE models to determine the demand substitution between commodities from different sources as a result of changes in relative prices. Because of their role, modellers are keen to know the correct elasticities for use in CGE models. Despite their importance, elasticities for South African agricultural commodities are outdated, leaving researchers to rely on value judgements. We address this limitation by estimating the Armington and export supply elasticities for individual and aggregate agricultural commodities using updated time-series data (1980–2016). The results for the two sets of trade elasticities show that estimates for an aggregate agriculture tend to be inelastic compared to estimates for an individual product, indicating a higher sensitivity of products to relative price changes. The Armington estimates were found to be closer to unity for the majority of products, suggesting that agricultural imports are imperfect substitutes for domestic products. The export supply elasticities for grains were found to be more elastic than for fruit and meat, implying that domestic grain production is relatively more responsive to price changes in the export markets. The long-run estimates for the two sets of elasticities were found to be larger than the short-run estimates for all agricultural products.

中文翻译：

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估计南非农产品的贸易弹性以用于政策建模

摘要 可计算一般均衡 (CGE) 模型通常用于分析政策变化的影响，因为它能够捕捉经济中的多部门相互联系。CGE 分析的结果在很大程度上取决于数据库、政策冲击和弹性。贸易弹性，例如阿明顿弹性，在 CGE 模型中发挥核心作用，用于确定由于相对价格变化而导致不同来源商品之间的需求替代。由于他们的角色，建模者很想知道在 CGE 模型中使用的正确弹性。尽管它们很重要，但南非农产品的弹性已经过时，使研究人员依赖于价值判断。我们通过使用更新的时间序列数据（1980-2016 年）估计单个和总体农产品的阿明顿和出口供应弹性来解决这一限制。两组贸易弹性的结果表明，与单个产品的估计相比，对农业总量的估计往往缺乏弹性，表明产品对相对价格变化的敏感性更高。对于大多数产品，阿明顿的估计更接近于统一，这表明农产品进口是国内产品的不完美替代品。发现谷物的出口供应弹性比水果和肉类的弹性更大，这意味着国内谷物生产对出口市场价格变化的反应相对更敏感。