  In this article we generalise POWHEG next-to-leading order parton shower
(NLOPS) simulations of vector boson production and vector boson production in
association with a single jet, to give matrix element corrected MENLOPS
simulations. In so doing we extend and provide, for the first time, an exact
and faithful implementation of the MENLOPS formalism in hadronic collisions. We
also consider merging the resulting event samples according to a phase space
partition defined in terms of an effective jet clustering scale. The merging
scale is restricted such that the component generated by the associated
production simulation does not impact on the NLO accuracy of inclusive vector
boson production observables. The dependence of the predictions on the
unphysical merging scale is demonstrated. Comparisons with Tevatron and LHC
data are presented.
