Analysis of a Modified Gompertz Model Based on Nonlinear Least Squares Method
Lizhi Yang *
School of Science, Southwest University of Science and Technology, Mianyang Sichuan, China.
Xiwang Xiang
School of Science, Southwest University of Science and Technology, Mianyang Sichuan, China.
Jiahao Cao
School of Science, Southwest University of Science and Technology, Mianyang Sichuan, China.
Yuanyuan Zhang
School of Science, Southwest University of Science and Technology, Mianyang Sichuan, China.
*Author to whom correspondence should be addressed.
Abstract
This paper proposes a modified Gompertz model with a constant free term based on the classical Gompertz model. Different from the three-sum method for determining the parameters of classical Gompertz model, this paper construct an optimization problem with the help of nonlinear least squares method. Moreover, employing the Levenberg-Marquardt method and the MATLAB software, the numerilal solution of the optimization problem is found. A numerilal example is provided in this paper. Finally, this paper uses this model to forecast the consumption level of Chinese rural residents, and the results illustrate the modified Gompertz model provides accurate prediction.
Keywords: Gompertz model, optimization problem, nonlinear least squares method, Levenberg-Marquardt method.