Validation of models with constant bias: an applied approach
Journal Title: Revista MVZ Cordoba - Year 2014, Vol 19, Issue 2
Abstract
Objective. This paper presents extensions to the statistical validation method based on the procedure of Freese when a model shows constant bias (CB) in its predictions and illustrate the method with data from a new mechanistic model that predict weight gain in cattle. Materials and methods. The extensions were the hypothesis tests and maximum anticipated error for the alternative approach, and the confidence interval for a quantile of the distribution of errors. Results. The model evaluated showed CB, once the CB is removed and with a confidence level of 95%, the magnitude of the error does not exceed 0.575 kg. Therefore, the validated model can be used to predict the daily weight gain of cattle, although it will require an adjustment in its structure based on the presence of CB to increase the accuracy of its forecasts. Conclusions. The confidence interval for the 1-α quantile of the distribution of errors after correcting the constant bias, allows determining the top limit for the magnitude of the error of prediction and use it to evaluate the evolution of the model in the forecasting of the system. The confidence interval approach to validate a model is more informative than the hypothesis tests for the same purpose.
Authors and Affiliations
Salvador Medina-Peralta, M. Sc| Universidad Autónoma de Yucatán, Facultad de Matemáticas, Apartado Postal 172 Cordemex, C.P. 97119, Mérida, Yucatán, México., Luis Vargas-Villamil, Ph. D *| Colegio de Postgraduados, Campus Tabasco, Periférico Carlos A. Molina Km. 3.5, Apartado Postal 24, C.P. 86500, Cárdenas, Tabasco, México.Correspondencia: luis@avanzavet.com, Jorge Navarro A, Ph. D| Universidad Autónoma de Yucatán, Facultad de Medicina Veterinaria y Zootecnia, Apartado Postal 4-116 Itzimná, C.P. 97100, Mérida, Yucatán, México., Leonel Avendaño R, Ph. D| Universidad Autónoma de Baja California, Instituto de Ciencias Agrícolas, 17 Boulevard Delta s/n, Ejido Nuevo León, C.P. 21705, Baja California, México., Luis Colorado M, M. Sc| Universidad Autónoma de Yucatán, Facultad de Matemáticas, Apartado Postal 172 Cordemex, C.P. 97119, Mérida, Yucatán, México., Enrique Arjona-Suarez, Ph. D| Colegio de Postgraduados, Programa en Estadística, Km 36.5 Carretera México-Texcoco, C.P. 56230, Montecillo, México., German Mendoza-Martinez, Ph. D| Universidad Autónoma Metropolitana, Xochimilco, Departamento de Producción Agrícola y Animal, Medicina Veterinaria y Zootecnia, Edificio 34, 3er piso, Calzada del Hueso 1100 Col Villa Quietud 04960, México D.F., México.
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