Fraction of blue ETGs as a function of σ_cl and L_X, separated into a relaxed cluster sample (blue open circles) and a merging cluster sample (filled grey circles). The solid black and blue lines indicate the average fraction for relaxed and merging clusters, respectively. The dotted lines correspond to the 1σ error for each sample. Merging clusters show a constant fraction of blue ETGs, while the fraction of blue ETGs varies considerably in the relaxed clusters.