Dependence of the average luminosity difference log(Gaia)−log(RRd) on the parallax shift (published minus shifted) for the RRd star sample. The separate lines correspond to log T_eff ZP shifts (relative to our adopted ZP as given in Sect. 2.3) of −0.005, 0.0 and +0.005. Error bars show the statistical errors of the mean differences. To avoid jamming, the error bars are shown only for one T_eff ZP shift (others are very similar). The shaded area indicates the range of the allowed EDR3 parallax correction to bring the Gaia and RRd luminosities into agreement.