ding vector of markdowns, ?? is a shared price sensitivity factor, and ?? is a vector of n shared seasonal indices; determining R2=1???(1???R2)*(n???1)/(n???1???c), where n is a number of observations, and c is a number of coefficients estimated, as a measure of average group score; and determining the similarity measure between the element and the center by one of using an array [??, ??] to defin