TESTING AGGREGATION CONSISTENCY ACROSS GEOGRAPHY AND COMMODITIES

Consistent aggregation of production data across commodities and states was tested using Lewbel's generalized composite commodity theorem (GCCT). This was the first empirical GCCT test for consistent geographic aggregation and was applied to two groups of states. Consistent commodity aggregation was tested in all states for two output groups and three input groups and in one state for a larger number of groups. Using a more powerful test procedure than previously applied to production data, most tests for commodity aggregation gave ambiguous results. Consistent geographic aggregation was generally supported across Pacific Northwest states but was ambiguous across all Western states. Key words: Aggregation, commodity, geographic, composite commodity theorem, multiple-comparison tests.