which is the radius of gyration of N scattering points located at distances ri. In mechanical terms, Rg can be interpreted as the radius of a thin ring that has the same mass and same moment of inertia as the body when this is centered around the same axis [12]. Furthermore, calculations indicate that the morphology of polymers in solution is not spherical in overall shape, but rather ellipsoidal [13]. In terms of their overall shape, branched polymers are more symmetric than linear ones [14]. This explains some of the differences between linear and branched polymers with respect to size exclusion. Similar arguments have been used to explain the failure of Rg to provide an appropriate size measure for the SEC of oligomers of polyethylene and polystyrene [15, 16].