Density distribution of the correlation between $\mathrm{Range}\stackrel{\sim }{[\mathrm{Fe}/\mathrm{H}]}(\mathrm{age})$ and ∇[Fe/H](τ) for 179 galaxies (black). These galaxies are chosen such that they have a linear gradient for (at least) their most recent 4 Gyr of star formation. Most galaxies exhibit a reasonable ability to have their ∇[Fe/H](τ) evolution recovered from $\mathrm{Range}\stackrel{\sim }{[\mathrm{Fe}/\mathrm{H}]}(\mathrm{age})$ (correlation ∼ − 1). This ability has a correlation with bar strength (colored lines), where stronger barred galaxies have a better recovery rate than weaker ones.