Context: The possible co-evolution between galaxies and their central supermassive black holes is supported by the similarity in shape between the Star Formation Rate Density (SFRD) and Black Hole Accretion Rate Density (BHARD) of the universe. Both trends peak around z~2 and decline to present day, however, due to selection effects they do not trace the same galaxies and thus represent a similarity in the global evolution of these two quantities, rather than local. To trace the local causal connection, if any, requires constructing both trends for the same sample in a self-consistent manner.