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, \(< s_{\rm{b}}^{2} >\), to that of an otherwise identical linear molecule, \(< s _{\rm{l}}^{2} >\), with the same relative molecular mass in the same solvent and at the same temperature, i.e. \(g = \frac{< s_{\rm{b}}^{2} >}{< s_{\rm{l}}^{2} >}\).