hereafter Paper I). The use of multiple methods allows for empirical determinations of the internal errors for each parameter, based on the range of reported values – typical internal errors for stars in the temperature range $4500$ K $\le$ $T_{\rm eff}$ $\le$ 7500 K are $\sim$ 73 K, $\sim$ 0.19 dex, and $\sim$ 0.10 dex, in $T_{\rm eff}$, log $g$, and \[Fe/H\], respectively. Allende Prieto et al. (2007, hereafter Paper III) point out that the internal uncertainties provided by the SSPP underestimate the typical random errors at high signal-to-noise ($S/N$) ratios because most methods in the SSPP make use of similar parameter indicators (e.g., hydrogen lines for effective temperature) and similar atmospheric models. Paper III empirically determines empirically external uncertainties of $\sim$ 130 K, $\sim$ 0.21 dex, and $\sim$ 0.11 dex, for $T_{\rm
eff}$, log $g$, and \[Fe/H\], respectively, by comparison with high-resolution spectroscopy ($7000 < R < 45,000$) of brighter SDSS-I/SEGUE that have been obtained with 8m$-$10m class telescopes. Somewhat larger errors apply to stars with temperatures near the extremes of the range above. The present study of Galactic globular and open cluster stars tests the SSPP’s ability to derive accurate results for stars with a wide range of 