A Study over Transformations of the Parameters of Richards Growth Model into the Biologically Meaningful Parameters

In this study, it is explained how the Richards model, which is one of the sigmoid growth models, is transformed into a mechanical model with biologically significant parameters such as maximum growth value, lag time and maximum specific growth rate. Detail transformations of the Richards growth model containing 4 parameters with biologically significant parameters calculated with the help of the first and second derivatives were given. In order to test the accuracy of this model, the model prediction values were analyzed by using the height data of the E. Camaldulensis Dehn tree by years. The estimated values of the biologically significant parameters of Richards growth model containing 4 parameters were compared with the estimated values of the modified Gompertz, Logistic and Bertalanffy models containing the other 3 parameters. Error Sum of Squares, Coefficients of Determination and Akaike Information Criteria were used as model evaluation criteria for all proposed models, and it was concluded that the Richards growth model containing 4-parameters predicted relatively better than other models.