During the first few centuries AD, Rome and the imperial frontiers were supplied with olive oil from the province of Hispania Baetica (southern Spain). Vast quantities of oil were exported in Dressel 20 amphorae. But how did the agricultural economy of Baetica relate to global demand and how did it change over time? The author focuses on relative changes in agricultural output, using a new method to model fluctuations in amphora production based on more than 1000 waster sherds collected from 23 amphora workshops in the Guadalquivir Valley. The chrono-proportional representation method indicates variation in production between individual workshops and wider production districts, contributing to assessments of the scale and organisation of the Roman economy.