error in our measurement of [\[C/Fe\]]{} by the following procedure. Let $\sigma_{\rm g}$ be the rms scatter (e.g., 0.328 dex in Figure \[fig:hicfe\]) from a Gaussian fit to the differences between our measurements and the literature values of [\[C/Fe\]]{}, and $\sigma_{i,\rm
HR}$ be the reported error from the $i$th star in the literature sample (LS). Then, the external error ($\sigma_{i,\rm ext}$) in our measured [\[C/Fe\]]{}of the $i$th object is derived by:

$$\sigma_{i,\rm ext} = \sqrt{\sigma_{\rm g}^{2} - \sigma_{i,\rm HR}^{2} - \sigma_{i,\rm SSPP}^{2}},
\label{eqn:sys}$$

where $\sigma_{i,\rm SSPP}$ is the random error of the SSPP determination for the $i$th entry, simply taken to be the internal uncertainty of our technique, estimated by following the procedure described in Section 2.3 above. In this equation, as the subscript indicates, $\sigma_{i,\rm HR}$ and $\sigma_{i,\rm SSPP}$ are based on the individual values for each target, whereas a value of $\sigma_{\rm
g}$ from the full sample is used. In other words, when calculating $\sigma_{i,\rm ext}$, $\sigma_{\rm g}$ is fixed for all objects, while $\sigma_{i,\rm HR}$ and $\sigma_{i,\rm SSPP}$ change for each star. Table \[tab:hiressam\] indicates there are eight stars without reported error estimates. For these stars, we adopt the average of the errors from other stars as 