We have posted a new version of our working paper, “The Welfare Effects of Supply-Side Incentives in Medicare Part D,” (PDF) written jointly with Francesco Decarolis and Maria Polyakova. The new version has extensive changes to the treatment of low-income subsidy enrollees, adjustments to the MA-PD outside option as an endogenous response to changes in the Part D PDP mechanism, a micro-founded basis for our treatment of vintage, and many, many other changes.