Relative internal residuals of our masses (left panels) and ages (right panels) estimated using spectra given by duplicate observations with similar spectral S/N for LAMOST RGB (top panels) and RC (bottom panels) stars. Black dots are the differences of duplicate observations of S/N differences smaller than 10%. Blue dots and error bars represent the median values and standard deviations (after dividing by ) of the relative residuals in the individual spectral S/N bins. Red lines indicate fits of the standard deviations as a function of spectral S/N.