Cumulative distributions of the luminosity scaled flux for PACS photometry of K and M Class II sources modeled in this paper. Distributions are built using the Kaplan-Meier estimator. The median and quartile values are shown with the vertical red lines, and the traditional median and quartiles are shown with the blue lines. The traditional method for determining lower quartiles fails in the situation where more than ~25% of observations result in nondetection, whereas this approach allows the determination of an upper limit to the quartile. The 160 μm median presented here represents an upper limit, as more than half the sources are undetected at this wavelength.