C IV line-width differences as a function of other C IV emission line properties. The top (bottom) panels show results based on the FWHM (line dispersion, σl). The left, middle, and right panels show the dependence of the difference on the C IV EW, kurtosis, and shape (FWHM/σl), respectively. The points are color-coded by the varying data quality of each subsample: S/N > 10 (orange), 10 < S/N < 5 (blue), and S/N < 5 (green). The solid black lines show the best-fit linear regression fit. The Spearman rank correlation coefficient, rs, and the probability that a correlation is found by chance, ﹩{P}_{{\rm{ran}}}﹩, are given in each panel.