European Review of Agricultural Economics Advance Access published online on September 18, 2007
European Review of Agricultural Economics, doi:10.1093/erae/jbm023
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Estimating technical efficiency under unobserved heterogeneity with stochastic frontier models: application to northern German dairy farms
University of Kiel, Germany
Corresponding author: Awudu Abdulai, Department of Food Economics and Consumption Studies, University of Kiel, Olshausenstrasse 40, 24118 Kiel, Germany. E-mail: aabdula{at}food-econ.uni-kiel.de
Received June 2006; Revision received June 2007. This article uses panel data estimation techniques to examine technical efficiency of individual dairy farms in northern Germany. To the extent that agricultural production is characterised by heterogeneous production conditions, estimation techniques that do not account for unobserved heterogeneity produce biased efficiency estimates. We therefore estimate a number of conventional panel data models and Greene's recently proposed true random-effects model, as well as an extension of the model to ascertain the effects of different specification on the production function and efficiency estimates. Our results appear to support theoretical expectations and previous findings according to which a specification that is both time-variant and also controls correlations between unobserved heterogeneity and the explanatory variables avoids heterogeneity bias and thus ensures consistent efficiency estimates.
Keywords: stochastic production frontiers, technical efficiency, panel data
JEL classification: Q12, D24