log(Ne/O) as a function of 12+log(O/H) (left) and the ionisation degree, O²⁺/O (right), for the DESIRED-E sample. The values of log(Ne/O) are calculated using the ICF(Ne) scheme by Izotov et al. (2006). The top panels show the points corresponding to SFGs (black squares) and the bottom panels the corresponding to H II regions (blue circles). Orange diamonds in the top right panel indicate the mean log(Ne/O) values considering bins in O²⁺/O. The blue continuous line included in the top left panel represents a linear fit to the data of SFGs. The dotted red line represents the mean value of the log(Ne/O) obtained for each kind of object. The black dashed lines and the grey bands show the solar 12+log(O/H) and log(Ne/O) and their associated uncertainties, respectively, from Asplund et al. (2021).