Grey convex relational degree and its application to evaluate regional economic sustainability

Grey relational degree analysis has been successfully adopted in various fields, but the existing grey relational analysis methods cannot deal with the three-dimensional panel data. In this paper, based on the grey convex relational degree for two-dimensional data and an approximation of the Hessian matrix for a discrete sequence, we propose a novel Grey convex Relational degree for the three-dimensional Panel Data (GRPD), which uses the similar characteristic of convexity among relevant factors to measure relational degree. An example of evaluation sustainable development is given to illustrate that the GRPD can more fully reflect the correlation degree among relevant factors.