KiDS-Bright galaxy SMF and the fractional errors. Upper panel: KiDS-Bright galaxy SMF (crosses) compared to the model from Wright et al. (2018), evaluated at the median redshift of our sample (black dashed line). The blue line and shaded region indicates the best-fit model and 68% confidence levels of our best-fit halo model (Eq. (22)). We caution that the quality of the fit cannot be judged by eye, because of the covariance in the data, between the data points and between the other observables. The reduced χ² value for this observable is 1.05 (d.o.f. = 14.58, p-value = 0.39), estimated using the method presented in Appendix C. Lower panel: Fractional errors on the data and the model, ΔΦ/δΦ.