We determine the degree of polymerization (DP or number of monomer residue) and average molecular weight of all polymer chains (either from NMR or GPC or MALDI) within any polymer. However, dispersity or heterogeneity or polydispersity index indicates the content/distribution of repeating units in all the polymer chains.  But, How could we determine the number of chains contains within that polymer? Is there any specific analysis available? More conveniently, suppose we would like to prepare a block copolymer using a macro-RAFT agent. How can we interpret the number of active chains in that macro-RAFT?