The branching index measures the effect of long-chain branches on the size of a macromolecule in solution. It is defined as g = >/>, where s is the mean square radius of gyration of the branched macromolecule in a given solvent, and s is the mean square radius of gyration of an otherwise identical linear macromolecule in the same solvent at the same temperature. A value greater than 1 indicates an increased radius of gyration due to branching.