Normalised cosmic variance as a function of n₁ for samples selected in B-band luminosity. The inverted triangles are those samples without a luminosity ratio imposed, and the triangles are those with a luminosity ratio applied (Table 8). Points at the same number density are offset when needed to avoid overlap. The dashed line marks the error-weighted average of , . The coloured area shows its 68% confidence interval. The grey area marks the 15% uncertainty expected from our parametrisation of the cosmic variance. A colour version of this plot is available in the electronic edition.