Illustration of the structure of a training set to train a shear estimator ĝ_i with an MSB cost function. The horizontal frames correspond to different “cases”, each containing different “realizations” of a galaxy. All galaxies of a case are simulated with the same true shear, and the same PSF. Despite the circular symmetry of the PSFs used in this illustration, the typical cosmic shear is too small to be noticed by eye.