Comparison of the integrated intensity of HCO⁺J = 4−3 with L_bol (left) and the integrated intensity of H₂O 1₁₀ −1₀₁ scaled to a distance of 200 pc (middle), as well as the FWHM of HCO⁺ vs. the FWZI of H₂O 1₁₀ −1₀₁ (right). 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.