Products of χ ² and MAD as a function of mean r-band magnitudes. The left panel is for simulated light curves, including constant stars (gray points), ab-type RR Lyrae (circles), and c-type RR Lyrae (squares). The color bar represents the input amplitudes for the simulated light curves. The inset figure is the zoomed-in version to highlight constant stars. The red line, given as χ ² × MAD = 0.045 r − 0.875, is adopted to separate RR Lyrae and constant stars. The right panel is for those stars, classified in SDSS DR16, with LOT light curves. The red line is same as the line shown in the inset figure on the left panel. We identified three RR Lyrae labeled as V1, V2, and V3. The light curve for the star with χ ² × MAD ∼ 4.5 was affected by outliers, and hence it was rejected as a RR Lyrae candidate.