Standardised Hubble residuals corrected for stretch (with a broken-α) and colour as a function of local environmental colour. Large blue points show the residuals binned by local colour, with the errorbars corresponding to the error on the mean. The scale of the fitted intrinsic scatter is shown in the top-right corner. The dashed line shows the step model. The full line illustrates the step model once convolved by a Gaussian with a standard dispersion equals to the mean local environmental measurement error (σ_{(g − z),local} ∼ 0.14), as we account for those errors in the step model.