Explaining the Food Purchasses of the Convent School at Saint-Cyr 1703-1788

The analysis of 85 years of food purchases at the rich, market-oriented Saint-Cyr convent School in the 18th century probes the determinants of consumption, its short-term variations and long-term shifts. Using time-series econometrics, we show that there is no equilibrium relationship between series of consumed quantities, prices and income that would be specific to the long term. Regarding short-term variations in consumption, the estimation of a demand system and the derivation of the corresponding elasticities allow us to show that market prices and budgetary constraints do play an important role, but also that this role remains limited, essentially because economic variables do not make it possible to account for the long-term evolutions. These unexplained long-run shifts suggest an interpretation in terms of structural changes in preferences, confirmed nonparametrically using revealed preference tests, which can be related – but not always – to the main subsistence crises that occurred throughout the century.