Median OH absorption velocity as a function of the HCN-vib luminosity relative to the total infrared luminosity. For sources with observations of the J = 3 − 2 transition, only this line is plotted. For sources with detections only in the J = 4 − 3 line, the HCN-vib luminosity is scaled down by a factor of 2.5, with an extra uncertainty of 20% included in the error bars. Squares, circles, diamonds, and triangles represent LINER, H II, Seyfert 1, and Seyfert 2 optical spectral types, respectively. Colors indicate the total infrared luminosity of each system. Upper limits (3σ) are indicated with arrows.