Document de travail du LEM 2006-13 Assessing managerial performance using non-parametric distance functions compared to technical and accounting ratio analysis: an application to French farms in Nord-Pas-de-Calais specialized in field crops Stéphane Blancard*, Jean-Philippe Boussemart**, Michel Debruyne*** * CESAER, INRA-ENESAD, Dijon, France ** LEM-CNRS, IESEG and Université Lille 3, France *** Université Lille 3, France