We discuss in a systematic way the extraction of neutrino masses, mixing
angles and leptonic CP violation at neutrino factories. Compared to previous
studies we put a special emphasis on improved statistical methods and on the
multidimensional nature of the combined fits of the nu_e -> nu_mu, \bar nu_e ->
\bar nu_mu appearance and nu_mu -> nu_mu, \bar nu_mu -> \bar nu_mu
disappearance channels. Uncertainties of all involved parameters and
statistical errors are included. We find previously ignored correlations in the
multidimensional parameter space, leading to modifications in the physics
reach, which amount in some cases to one order of magnitude. Including proper
statistical errors we determine for all parameters the improved sensitivity
limits for various baselines, beam energies, neutrino fluxes and detector
masses. Our results allow a comparison of the physics potential for different
choices of baseline and beam energy with regard to all involved parameters. In
addition we discuss in more detail the problem of parameter degeneracies in
measurements of delta_CP.Comment: 29 pages, 14 fugure