We investigate the effect of ground-state correlations due to the zero-point energy of dipole oscillations on the elastic electron scattering and on the dipole sum rules. We describe the ground-state correlations using the generator coordinate method where the choice of the generator coordinate states is guided by the Goldhaber-Teller model of the giant dipole resonance. In this framework we show that the effect of the ground-state correlation is only to change the amplitude of the relative motion of the protons as a whole against the neutrons as a whole. This effect can make a large change in the inverse energy-weighted photoabsorption cross-section, as suggested by experiment, with only a small change in the form factor for elastic electron scattering. Since our model can be considered as a restricted RPA, the same effect should appear qualitatively in the more sophisticated calculations.