Cross-calibration of metallicity determination methods. On the left, we illustrate the transformation from metallicities following the Tremonti et al. (2004) method to those based on Kobulnicky & Kewley (2004). On the right, we depict the conversion from Kobulnicky & Kewley (2004) metallicities to those derived using the Tremonti et al. (2004) method. The blue circles represent data points sourced from the OSSY catalogue, while the orange line represents a third-order polynomial fit to the OSSY data.