A parameter, g, characterizing the effect of long-chain branches on the size of a branched macromolecule in solution and defined as the ratio of the mean-square radius of gyration of a branched molecule, < s_b² >, to that of an otherwise identical linear molecule, < s_l² >, with the same relative molecular mass in the same solvent and at the same temperature, i.e. g = < s_b² > / < s_l² >.