Top row, left panel: sensitivity for the detection of single stars from synthetic clusters as a function of the multiplier of the baseline observational error σ = 0.003 mag. The dashed line marks the 95% value. The cluster fiducial lines for the test were data driven (see text for details). Top row, right panel: specificity for the detection of single stars from synthetic clusters (data-driven fiducial line). The dashed green line marks the 90% value and represents a preferred target, while the purple line marks the 80% value and represents a minimum requirement. Bottom row: same as in the top row, but adopting the theoretical isochrone as the fiducial line.