Study on the second grey relational grade and its properties

Purpose – The purpose of this paper is to propose a second relational grade based on the general grey relational grade and analyze several of its properties.Design/methodology/approach – Grey system theory. The paper proposes and studies second grey relational grade, establishes second grey relational formula, and studies several characteristics of second grey relational formula.Findings – Proposing a second relational grade proved it could solve the problem of the parallelism partly and weaken relativity of space position.Research limitations/implications – Until now, the problem of the consistency could not be solved, nor could the problem of the effect which keeps the sequence the same.Practical implications – The precision of the grey forecasting model could be strengthened if used in the forecasting model.Originality/value – The general relational grade only thinks over the relation between two sequences but does not involve the relation in one sequence. The second relational grade considers these tw...