appending together the data sets corresponding to all entities assigned to a cluster, and performing a least square regression; assuming m entities with n data elements each, using a model fitted in log space of lnY=lnA+??M+??+ln??, where Y is a vector of size mn, A is a matrix of [a1 a2 . . . am], with a1 being a base sale for data set 1 and am being a base sale for data set m, M is a correspondi