Before revision:   Importantly, the number of equations that we obtain in this way is independent of the number of considered cells such that the method scales to arbitrary population sizes.
After revision:  Since the number of obtained equations grows combinatorially with number of considered cells, we employ a previously proposed model reduction technique, which exploits symmetries in the underlying moment dynamics. Importantly, the number of equations that we obtain in this way is independent of the number of considered cells such that the method scales to arbitrary population sizes.