Comparison of the integrated intensity of H₂O 1₁₀ −1₀₁ linearly scaled to a distance of 200 pc with various source (top) and outflow-related (bottom left and middle) properties, as well as the integrated intensity normalised by L_bol vs. the evolutionary indicator (bottom right) proposed by Bontemps et al. (1996). The number of sources, correlation coefficient and probability that the correlation is not just due to random distributions in the variables are shown in the upper-left of each panel.