Distributions of IRAS 25/60 μm ratios in various samples. Top: histogram showing the distribution in the IRAS revised bright galaxy sample (RBGS). Middle: stacked histogram showing the distribution in the sample that would have resulted if sources were selected based on the total infrared luminosity (between 8 μm and 1000 μm) instead of the far-infrared luminosity (between 40 and 400 μm), with the CON-quest sample marked using a darker shade. Bottom: empirical distribution functions of the RBGS (solid black), the CON-quest sample (dash-dotted gray), the additional sources required to complete an infrared selected sample (dotted gray), and the total infrared selected sample (dashed red).