(Left) The i-th component of the conditional posterior optimized with respect to the shape parameter so that close to the point of linearization with some constant c (Appendix A). The gray curves correspond to IG and the black ones to G hyperprior. The solid, dashed and dash-dotted curves have been obtained with , and , respectively. In each case the scale parameter is . The maximizers match approximately, i.e., , when (solid) and the optimizer is . (Center) The relative scale deviation w.r.t. as a function of the optimizer , vanishing when . (Right) The optimizer as the function of .