1. A non-transitory computer readable medium having computer instructions stored therein, which when executed by a computer processor performs a method for determining the similarity between a first multivariate data set and a second multivariate data set comprising: i) representing the data of each multivariate data set in matrix form to yield a multivariate data matrix, wherein each multivariate data matrix has the same dimensions; ii) calculating the magnitude of an additive and subtractive combination of each multivariate data matrix; iii) introducing a penalty parameter to set a detectable limit of variance between said first multivariate data set and said second multivariate data set, and using said penalty parameter in combination with the results of step ii) to determine a similarity value; wherein said determined similarity value indicates the variance between said first multivariate data set and said second multivariate data set.