Total column density N_H of the ionised AGN wind versus the radio-loudness parameter R of the jet. Each data point corresponds to one radio-loud AGN in our sample. For those AGN with multiple absorption components the sum of the column density N_H of the components is shown. There is a significant inverse correlation between N_H and R. The Spearman’s rank correlation coefficient r_s and the null hypothesis probability p_null of the correlation between the parameters are shown inset. The data have been fitted with the power-law function of Eq. (1) shown in dashed black line. The shaded grey region represents the 1σ uncertainty around the best-fit line.