2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/183892An NLO QCD analysis of the ZEUS data on $e^+ p$ deep inelastic scattering together with fixed-target data has been performed from which the gluon and quark densities of the proton and the value of the strong coupling parameter, $α_s(M_Z^2)$, have been extracted. The study includes a full treatment of the experimental systematic uncertainties, including point-to-point correlations. Different ways of incorporating correlated systematic uncertainties into the fit are discussed and compared.8 pages, 1 figure. Invited talk at the Conference on Advanced Statistical Techniques in Particle Physics, March 18-22 2002, Durham, UKHigh Energy Physics - Phenomenologytext