A semiparametric mixture model is characterized by a non-parametric mixing distribution <b><scriptface>Q</scriptface></b> (with respect to a parameter <b>"θ"</b>) and a structural parameter <b>"β"</b> common to all components. Much of the literature on mixture models has focused on fixing <b>"β"</b> and estimating <scriptface>Q</scriptface>. However, this can lead to...