Grey I-PRAY forecasting method based on the difference information principle of Grey system

For those sequence that the discrete degree is large, based on GM(1, 1) model, Prof. Deng Ju-long proposed a forecasting method called grey envelope forecasting for its interval forecasting. But the envelope forecasting has two shortcomings: one is that its forecasting value is influenced by personal subjective desire; the other is that local information is ignored. Aiming at conquering the two problems, an objective forecasting method, called Grey PRAY forecasting, was put forward by Chen Yong-ming in 2007. However, the Grey PRAY forecasting method makes part use of local information. In this paper, in order to make full use of local information, based on the difference information principle of gray system theory, the mathematical tool, scalar product of vectors, is employed to generate an objective forecasting method, called Grey I-PRAY which connotes the improvement of Grey PRAY method.