Sunday, November 12, 2017

"Indiana Jones, Economist?!"

Professor Tabarrok is, as they used to say, over the moon.

From Marginal Revolution:
In a stunningly original paper Gojko Barjamovic, Thomas Chaney, Kerem A. Coşar, and Ali Hortaçsu use the gravity model of trade to infer the location of lost cities from Bronze age Assyria! The simplest gravity model makes predictions about trade flows based on the sizes of cities and the distances between them. More complicated models add costs based on geographic barriers. The authors have data from ancient texts on trade flows between all the cities, they know the locations of some of the cities, and they know the geography of the region. Using this data they can invert the gravity model and, triangulating from the known cities, find the lost cities that would best “fit” the model. In other words, by assuming the model is true the authors can predict where the lost cities should be located. To test the idea the authors pretend that some known cities are lost and amazingly the model is able to accurately rediscover those cities.

Here from the paper is more detail. Each step is an accomplishment and the final product is something completely unexpected. Bravo!
Our first contribution is to extract systematic information on commercial linkages between cities from ancient texts. To do so, we leverage the fact that the ancient records we study can be transcribed into the Latin alphabet, allowing all texts to be digitized and parsed. We automatically isolate, across all records, the tablets which jointly mention at least two cities. We then systematically read those texts, which requires an intimate knowledge of the cuneiform script and Old Assyrian dialect of the ancient Akkadian language that the records are written in. Taking individual source context into account, this analysis relies exclusively upon a subset of records that explicitly refer to journeys between cities and distinguishes whether the specific journey was undertaken for the purpose of moving cargo, return journeys, or journeys undertaken for other reasons (legal, private, etc.)....