discuss the implications for the ${\hbox{$M_{\star}$--$Z$--${\rm SFR}$}}$ relation. Finally, we briefly summarize our results in Section \[sec:conc\].

Data {#sec:data}
====

Sample Selection {#sec:sample}
----------------

Our sample of galaxies is derived from the SDSS Data Release 7 (DR7; @Abazajian09). We begin with the ${\hbox{MPA/JHU}}$ catalog of galaxies with stellar masses [@Kauffmann03b], SFRs [@Brinchmann04; @Salim07], and oxygen abundances [@Tremonti04 hereafter T04]. We discard AGN dominated galaxies with the standard Baldwin-Philips-Terlevich (BPT) diagram [@Baldwin81] and the criterion for star forming galaxies from @Kauffmann03a:

$$\begin{gathered}
\log([\text{\ion{O}{iii}}]~\lambda5007 / {\hbox{H$\beta$}}) < \\
   0.61[\log([\text{\ion{N}{ii}}]~\lambda6583/{\hbox{H$\alpha$}}) - 0.05]^{-1} + 1.3.
\label{eq:sf}\end{gathered}$$

Our S/N requirements are the same as those presented in @Andrews13. We restrict our sample to galaxies with , , and ${\hbox{[\ion{N}{ii}]~$\lambda$6583}}$ detected at $>5\sigma$. For galaxies with ${\hbox{[\ion{O}{iii}]~$\lambda$5007}}$ detected at $>3\sigma$, we apply the selection criteria shown in Equation \[eq:sf\]. In order to include galaxies with high metallicity (and inherently weak ${\hbox{[\ion{O}{iii}]~$\lambda$5007}}$) we include galaxies with ${\hbox{[\ion{O}{iii}]~$\lambda$5007}}$ detected at $<3 \sigma$ but $\log({\hbox{[\ion{N}{ii}]~$\lambda$6583}}/{\hbox{H$\alpha$}}) < 0.4$.

We also take significant care to inspect low mass galaxies ($\log[M_*] < 8.6$) and remove galaxies with poor photometric deblending (flagged with `DEBLEND_NOPEAK` or `DEBLENDED_AT_EDGE`) or otherwise spurious stellar mass determinations. These selection cuts leave a total of 208,529 galaxies in our 