The law of one price: a test based on prices for selected inputs in New Zealand agriculture
利用新西兰农业15种投入品的价格数据检验一价定律，发现短期不支持该定律，长期结果不一，提示政策建模中不宜普遍假设一价定律成立。
The law of one price (LOOP) is an essential foundation of both the pure theory of trade and monetary theory. Strictly speaking, the law relates to prices of individual commodities. However, empirical tests of LOOP have often relied on aggregated data. In this paper, a model is derived and estimated using price data for 15 selected inputs in New Zealand agriculture. The results offer no support for the LOOP in the short run, and the results for the long run are mixed. It may be inappropriate, therefore, to assume that the LOOP holds generally in modelling exercises, particularly when models are used for policy purposes.