Gc. Davis et al., Aggregation without separability: Tests of the United States and Mexican agricultural production data, AM J AGR EC, 82(1), 2000, pp. 214-230
The generalized composite commodity theorem (GCCT) and testing procedure is
extended to Lest for consistent aggregation of the United States and Mexic
an agricultural production data in each category for which earlier tests re
jected homothetic separability. Nonrejected GCCT and separability hypothese
s provide empirical support for aggregating all the United Stales agricultu
ral outputs into as few as two categories: crops and livestock. Mexican agr
icultural outputs also can be aggregated into as few as two categories. Sup
port for aggregating all outputs into a single category is ambiguous in bot
h countries and is only provided by the GCCT.