Average multiplicative bias, m = (m_ϵ1 + m_ϵ2)/2, as a function of (a) the galaxy resolution, R, and (b) the signal-to-noise ratio, S/N. Each point is measured on the same number of simulated galaxies and the error bars are estimated using bootstraps. For a comparison we also display in the background the weighted distribution of the two definitions of R and the S/N in the real data for the dense shape samples (pink: lensfit; blue: DEIMOS). The solid lines show the polynomial fit to m(R) and m(S/N), which guided the construction of the two-dimensional bias surface.