Comparison between two sets of values of T_eff: (i) taken from the literature and (ii) derived from the (R – I)_C/T_eff correlations that have been derived by M15 and B12. Continuous line: the correlation that would exist if there was an exact one-to-one correspondence between the two sets of T_eff. Dashed line: the best-fit correlation when the data are smoothed by a Gaussian of FWHM 30 K. Note that there exists a good overall agreement between the smoothed data and the expectations of a one-to-one correspondence.