QUANTIFICATION OF AGGREGATION BIAS IN REGIONAL AGRICULTURAL LAND-USE MODELS - APPLICATION TO GUACIMO COUNTY, COSTA-RICA

Different specifications of a land use model for Guacimo county in Cos ta Rica were used to quantify various sources of aggregation bias, inc luding variation in farm resource endowments within and between repres entative farm classes; spatially variable prices; and labor market int er-dependencies between farm classes. The results indicate that adequa te treatment of the farm level in regional land use analysis requires proper classification of individual farms in representative farm class es, as well as explicit modelling of inter-dependencies between such c lasses. Aggregation bias introduced by the assumption of spatially fix ed farm-gate prices is insignificant for regions with reasonable infra structure quality and relatively small distances between farms and mar kets. Aggregation bias caused by variation in resource endowments with in farm classes cannot be eliminated, but should be minimized, undersc oring the importance of a proper farm classification. (C) 1998 Elsevie r Science Ltd. All rights reserved.