of the effect from global stellar mass in shaping the local metallicity. This result has been interpreted as the evidence of metal loss by the galactic winds from galaxy potential wells in the literature, because more massive galaxies construct deeper potential wells and are less efficient in metal loss [e.g. @Tremonti2004; @Mannucci2010a; @Sparre2017].

The Correlation Strength Between Stellar Mass, Stellar Mass Surface Density And Metallicity {#subsec:metallicity-correlation}
-------------------------------------------------------------------------------------------

In this section, we investigate the strength of dependence of metallicity on $M_*$ and $\Sigma_*$, and tackle the question which one is more closely related to the local metallicity in galaxies. For a given galaxy, we radially bin the spaxels so that $\Delta R/R_e=0.3$. We use the median values of metallicity and $\Sigma_*$ in each radial bin in the analysis below (hereafter “radial bin sample”), though excluding the bins with less than 20 spaxels. Compared to using all the relevant spaxels, this strategy ensures an even weight for different galactic radii, and suppresses the effect of outliers. In addition, the metallicity and stellar distributions are roughly azimuthally symmetrical, thus the medians of $Z$ and $\Sigma_*$ in the radial bins appear representive.

Following [@Yang2017], we perform a partial correlation (PCOR) analysis on our data, 