1. A numerical modelling apparatus, the apparatus comprising: an input unit arranged to receive signals containing data having information relating to a set of assets; a processor unit arranged to: a) provide a Risk Relation Matrix v having a plurality of elements, wherein each of the elements represents a relationship of risk related to a respective pair of the assets and each element is given by a scalar product of two risk vectors, such that each of the assets has an associated risk vector according to the elements of the risk relation matrix; b) decompose the Risk Relation Matrix v into eigenvectors and eigenvalues according to: 
 V=E·Λ·E′ wherein E is a set of eigenvectors of the risk matrix v in columns, Λ is the corresponding diagonal eigenvalue matrix, and E′ is the transpose of E; and c) derive components of each of the risk vectors in the basis of unit independent risks by the corresponding row of the matrix product E·Λ 1/2 relating to each of the assets; and an output unit arranged to output the components of each of the risk vectors as a risk vector data set onto a tangible computer-readable recording medium or a display device.