Acoustic-scale distance ratio r_s/D_V(z) divided by the distance ratio of the Planck base ΛCDM model. The points are colour-coded as follows: green star (6dF); purple squares (SDSS DR7 as analysed by Percival et al. 2010); black star (SDSS DR7 as analysed by Padmanabhan et al. 2012); blue cross (BOSS DR9); and blue circles (WiggleZ). The grey band shows the approximate ± 1σ range allowed by Planck (computed from the CosmoMC chains).