thought of as the “benefit" of observing a star. The “cost" of observing a star is the exposure time $\tau$. Thus, a reasonable prioritization metric is simply $C/\tau$, the benefit-to-cost ratio. The calculation of this ratio appears elementary, but combining completeness with exposure time is non-trivial and the method used can significantly impact the yield estimates as well as how the yield responds to changes in mission design parameters.

### A Review of Prioritization Methods

Completeness and exposure time both depend on a value of $\Delta {\rm mag}_{\rm obs}$, which defines the dimmest planet that can be detected at the desired S/N. Traditionally, models have chosen a value of $\Delta {\rm mag}_{\rm obs}$ for each star, but the choice of $\Delta {\rm mag}_{\rm obs}$ varies widely in the literature. @2010ApJ...715..122B assumed a fixed value of $\Delta {\rm mag}_{\rm obs}=\Delta {\rm mag}_{\rm floor}=26$ for all stars in the target list, where $\Delta {\rm mag}_{\rm floor}$ is the systematic noise floor, beyond which a point source can never be detected at the required S/N. We refer to this method as a strict limiting search observation (SLSO) method. An SLSO method is both straight-forward and computationally fast. However, exoEarth candidates around late type 