Volume 24, Number 6-7, September-November 2004
Crop model STICS (Simulateur mulTIdisciplinaire pour les Cultures Standard)
Page(s) 351 - 365
Agronomie 24 (2004) 351-365
DOI: 10.1051/agro:2004033

Comparison of parameter estimation methods for crop models

Marie Tremblay and Daniel Wallach

Unité Mixte de Recherche A.R.C.H.E., INRA Toulouse, BP 27, 31326 Castanet-Tolosan Cedex, France

(Received 3 June 2003; accepted 10 May 2004)

Abstract - Crop models are important tools in agronomic research, a major use being to make predictions. A proper parameter estimation method is necessary to ensure accurate predictions. Until now studies have focused on the application of a particular estimation method and few comparisons of different methods are available. In this paper, we compare several parameter estimation methods, related, on the one hand, to model selection, and on the other, to ridge regression based on an analogy to a Bayesian approach. The different methods are applied to a simplified crop model derived from the STICS model, using simulated data. The criteria for comparison are prediction error and errors in the parameter estimates. Among the methods of model comparison a version of the Schwarz criterion, corrected for small samples and with maximum and minimum bounds for each parameter, is the preferred method. Ridge regression is found to be superior to this best method of model selection.

Key words: parameter estimation / crop model / model selection methods / ridge regression

Corresponding author: Marie Tremblay

© INRA, EDP Sciences 2004