  Our aim is to quantify the impact of systematic effects on the inference of
cosmological parameters from cosmic shear. We present an end-to-end approach
that introduces sources of bias in a modelled weak lensing survey on a
galaxy-by-galaxy level. Residual biases are propagated through a pipeline from
galaxy properties (one end) through to cosmic shear power spectra and
cosmological parameter estimates (the other end), to quantify how imperfect
knowledge of the pipeline changes the maximum likelihood values of dark energy
parameters. We quantify the impact of an imperfect correction for charge
transfer inefficiency (CTI) and modelling uncertainties of the point spread
function (PSF) for Euclid, and find that the biases introduced can be corrected
to acceptable levels.
