IRX–β scatter of our sample color-coded with metallicity. Points denote the VIPERS sample binned by β, every bin contains the same number of galaxies (160 galaxies), except the last bin (containing 89 galaxies). The best fits from the literature and the best fit of our sample are also shown. Colors and line-styles of these fits are the same as in Fig. 6. The arrow represents the trend of the metallicity, based on the scattered distribution (the direction is from the mean of the bottom 30th percentile of the distribution of metallicity to that of the top 70th percentile). The angle is between the arrow and the x axis.