SDSS/SEGUE spectra, while “HR” denotes the high-resolution determination. An average systematic offset of 0.128 dex, with a standard deviation of 0.328 dex, is noticed from the Gaussian fit to the residuals (SSPP$-$HR) between the two estimates, shown in the upper-left panel. Note that this offset is not unexpected, given the use of our improved carbon-enhanced model atmospheres (carbon-enhanced models are not used in most high-resolution abundance analyses due to the difficulty of generating such models), and the different molecular linelists employed by the high-resolution analyses. As the offset is small, and in any case much lower than the rms scatter, we do not attempt to adjust our measurements. There are also no strong trends with either \[Fe/H\] or [$\log~g$]{}, as shown in the lower panels. The left-pointing arrows in the upper-right panel, and the upward pointing arrows in the lower two panels, indicate upper limit estimates on [\[C/Fe\]]{}drawn from the literature (they are reported as detections with lower values from the SSPP).

As the uncertainty in our measured [\[C/Fe\]]{} includes both external and internal random errors, and the abundances that we employ from the literature (based on the high-resolution analyses) carries its own errors as well, we quantify the total 