Statistical estimate and correction of the LEP optics imperfections

Statistical estimates of the perturbation of the linear lattice functions (Twiss parameters, dispersion and betatron coupling) are made for LEP; they complement imperfection studies by simulation and provide a better understanding of the relative importances of the imperfection sources. They allow in addition to draw some scaling laws which demonstrate why imperfections do not simply scale with machine size. Estimates of the resulting luminosity losses help in defining the correction needs and their resolution