Sample statistics of number counts in cells as a function of flux density threshold. Shown are the clustering parameter n_c (variance over mean), which is expected to be one for the Poisson distribution, the skewness g₁ and excess kurtosis g₂ − 3 with error bars calculated from 100 bootstrap samples. On the left hand side for the LoTSS-DR1 radio source catalogue, on the right hand side for the LoTSS-DR1 value-added source catalogue. From top to bottom: mask d and masks 2 and 1.