Angular auto-correlation function measurement for the LBG sample. This measurement is used to test if the sample is contaminated. If the sample were highly contaminated, ﹩\omega (\theta )=0﹩ at every scale and a power-law fit with slope β would be consistent with zero. We find that the LBG sample is not highly contaminated, given their power-law shape in this plot, which is well fitted by ﹩\omega (\theta )=21.56\,{\theta }^{-1.07}﹩ (red line).