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α: calibrated so average coauthorship-adjusted count equals average raw count
We study the classic sequential screening problem in the presence of ex post participation constraints. We establish necessary and sufficient conditions that determine when the optimal selling mechanism is either static or sequential. In the static contract, the buyers are not screened with respect to their interim type and the object is sold at a posted price. In the sequential contract, the buyers are screened with respect to their interim type and a menu of quantities is offered.