The four-point models have one fewer parameter because the molecular geometry is not being optimized, but more accurate results are obtained for the validation properties; in particular, the diffusion coefficient of TIP4P-ST agrees closely with experiment, and the O-O radial distribution function of TIP4P-ST agrees with experiment at a similar level as the TIP4P-Ew, TIP3P-FB and TIP4P-FB models. The improved ability of four-point models to reproduce experimental properties has previously been attributed to the model's ability to predict the correct quadrupole moment of the water molecule.