  Understanding the links between the activity of supermassive black holes
(SMBH) at the centres of galaxies and their host dark matter haloes is a key
question in modern astrophysics. The final data release of the SDSS-IV eBOSS
provides the largest contemporary spectroscopic sample of galaxies and QSOs.
Using this sample and covering the redshift interval $z=0.7-1.1$, we have
measured the clustering properties of the eBOSS QSOs, Emission Line Galaxies
(ELGs) and Luminous Red Galaxies (LRGs). We have also measured the fraction of
QSOs as a function of the overdensity defined by the galaxy population. Using
these measurements, we investigate how QSOs populate and sample the galaxy
population, and how the host dark-matter haloes of QSOs sample the underlying
halo distribution. We find that the probability of a galaxy hosting a QSO is
independent of the host dark matter halo mass of the galaxy. We also find that
about 60\% of eBOSS QSOs are hosted by LRGs and about 20-40\% of QSOs are
hosted by satellite galaxies. We find a slight preference for QSOs to populate
satellite galaxies over central galaxies. This is connected to the host halo
mass distribution of different types of galaxies. Based on our analysis, QSOs
should be hosted by a very broad distribution of haloes, and their occurrence
should be modulated only by the efficiency of galaxy formation processes.
