Distefano Tiziano, Chiarotti Guido, Laio Francesco, Ridolfi Luca
Department of Environmental, Land and Infrastructure Engineering, Politecnico di Torino, Corso Duca degli Abruzzi, 24, Torino 10129, Italy.
Ecol Econ. 2019 May;159:122-132. doi: 10.1016/j.ecolecon.2019.01.010.
Global food prices are typically analysed in a time-series framework. We complement this approach by focusing on the spatial price dispersion of the country-pair bilateral trade in the international food trade network (), for ten relevant commodities. The main purposes are to verify if the Law of One Price () holds and to investigate the emergence of randomness in the price-formation mechanism. We distinguish between the "internal" variance, which indicates the magnitude of price discrimination, and the "external" variance, that is a measure of price dispersion. We find that, for some commodities, spatial price dispersion is remarkable and persistent over time (i.e., failure of the ) and that there exists a strict correlation between price spikes and peaks in spatial price variability. We test whether the price distribution can be replicated through a stochastic process of extraction. Surprisingly, the actual distribution of prices, for several commodities, is well described by a random distribution. Then, the process of data aggregation is not neutral because the information at the micro-level scale might be lost at the macro-scale, due to the complexity of the . Finally, we discuss some possible economic explanations of these outcomes and the main methodological, environmental, and policy consequences.
全球食品价格通常在时间序列框架内进行分析。我们通过关注国际食品贸易网络中十个相关商品的国家双边贸易的空间价格离散度来补充这种方法。主要目的是验证一价定律是否成立，并研究价格形成机制中随机性的出现。我们区分了表示价格歧视程度的“内部”方差和作为价格离散度度量的“外部”方差。我们发现，对于某些商品，空间价格离散度在一段时间内显著且持续存在（即一价定律失效），并且价格峰值与空间价格变异性峰值之间存在严格的相关性。我们测试价格分布是否可以通过随机抽取过程来复制。令人惊讶的是，几种商品的实际价格分布可以用随机分布很好地描述。然后，数据汇总过程并非中立，因为由于[此处原文缺失具体原因]的复杂性，微观层面的信息可能会在宏观层面丢失。最后，我们讨论了这些结果的一些可能的经济解释以及主要的方法、环境和政策后果。
