Selected non-parametric measures of diversity properties (Stirling 2006f,o). N, number of categories of elements; ln, logarithm (usually natural); pi, proportion of system comprises category i; n, number of attributes displayed by elements; σ, standard deviation of attributes within categories; μ, mean of attributes within categories; f (dij), function of distance in disparity space between categories i and j; DW(S), aggregate disparity of system S; dW(i, S\i), distance in disparity space between category i and the nearest remaining element in S if i is excluded.