On an individual basis, the values of the Malmquist productivity indices for groups A, B, C and D are depicted in the four diagrams depicted in Figs 1–4. The hospitals have been arranged clock-wisely in ascending order according to their MPI values (blue line) whilst the first occurrence of an MPI value >1 is denoted by the yellow dots. The MPI line is surrounded by two spirals that correspond to the bootstrap calculated for upper and lower values for the 95% confidence interval. Furthermore, the geometric MPI mean for each group is depicted as a yellow circle. From the diagrams, it is easily deducted that the number of hospitals that experienced overall productivity progress (MPI>1) for the groups A, B, C and D are 14/21 (= 66.6%), 17/33 (= 51.5%), 21/30 (= 70%) and 20/23 (= 87.0%) respectively. The MPI values span in the range from 0.7–2.06 (group A), 0.39–1.64 (group B), 0.56–2.72 (group C) and 0.56–2.32 (group D).