Product Aggregation Bias as a Specification Error in Demand Systems
指出所有需求研究都涉及产品加总，这可能导致加总偏误，并提出一个简单方法将这种偏误纳入需求系统，通过似然比检验进行检验，实证表明正确加总的重要性。
Abstract Inherent in all demand studies is some form of product aggregation which can lead to product aggregation bias. This article develops a simple procedure for incorporating product aggregation bias in demand systems that permits testing of product aggregation bias with a standard likelihood ratio test. An empirical illustration of the procedure demonstrates the importance of proper product aggregation.