electron temperature, electron density, the flux ratios of the strong lines relative to ${\hbox{H$\beta$}}$, and the `IRAF/STSDAS` *nebular.ionic* routine [@DeRobertis87; @Shaw95]. Atomic data plays a critical role in direct method temperature determinations [@Kennicutt03]. For example, @Berg15 noted a substantial difference in temperatures when using updated collision strengths. The temperatures are largely unaffected by the updated atomic data, so we utilize the *nebular.temden* routine without modification. The uncertainties in the abundances of individual ionic species are determined with the same Monte Carlo simulations used to determine the uncertainties in electron temperatures. The ionic abundance uncertainties are used to analytically calculate the uncertainty in the total abundances.

We assume the total oxygen abundance is given by $$\frac{\rm O}{\rm H} = \frac{\rm O^+}{\rm H^+} + \frac{\rm O^{++}}{\rm H^+}.$$ Historically, the temperature of the high ionization region, $T_3$, is measured using the direct method and $T_2$ is then inferred using the ${\hbox{$T_2-T_3$}}$ relation. At high masses, we are unable to measure $T_3$ but often have a measurement of $T_2$. We use the stacks where both $T_2$ and $T_3$ are measured to infer a ${\hbox{$T_2-T_3$}}$ relation that results in the best agreement between measured and inferred $T_3$. As in @Andrews13, this is done using a 