Average number of low-Σ (filled magenta squares) and high-Σ (filled cyan triangles) MPGs as a function of local density δ derived from 100 mass-matched samples. The counts are corrected for the selection function of the VIPERS survey. Error bars include the Poisson fluctuations and the error on the mean. The four δ bins correspond to the four quartiles of the MPG (1 + δ) distribution. Open symbols are the mean number of low- and high-Σ MPGs that are effectively observed (i.e., not corrected for the selection function) over 100 iterations. The ordinate scale on the right-hand side refers to the uncorrected counts.