Utilising data from the direct detections of compact binary coalescences (CBCs) in the first
three observing runs of the LIGO-Virgo-KAGRA Collaboration (LVK), we estimate the redshift
dependence of the binary black hole (BBH) population. Specifically, we search for signs that
the mass distribution of BBHs varies over cosmic history. The detection of such variation would
allow us to gain more knowledge about the population itself, but also the formation channels of
CBCs throughout the Universe. However, detectable CBCs primarily occur at low to moderate
redshift, limiting our ability to constrain the high redshift behaviour of the quantities of interest.
Nevertheless, current upper limits on the gravitational-wave background (GWB) from CBCs can
be used as an additional source of information to uncover the high redshift behavior of the merger
rate and the mass distribution. We implement this joint CBC and GWB analysis in a Bayesian
framework, allowing us to construct posteriors for the parameters describing the population of
CBCs and their evolution with redshift.