Orange Juice and Weather
研究冷冻浓缩橙汁这一特殊商品的价格与天气的关系，指出其生产高度集中于佛罗里达中部，天气是影响产量的主要外生因素，适合分析价格与外部价值决定因素的互动。
Frozen concentrated orange juice is an unusual commodity. It is concentrated not only hydrologically, but also geographically; more than 98 percent of U.S. production takes place in the central Florida region around Orlando.' Weather is a major influence on orange juice production and un- like commodities such as corn and oats, which are produced over wide geographical areas, orange juice output is influenced primarily by the weather at a single location. This suggests that frozen concentrated orange juice is a relatively good candidate for a study of the interaction between prices and a truly exogenous determinant of value, the weather.