In this paper, we design the optimal procurement mechanisms when bidders are privately informed on efficiency and on observable but neither verifiable nor contractible quality. We show that most of the optimal procurement institutions are mixed procedure implying both separation and pooling. Thus, the existing take-it-or-leave-it offers and procurement auction appear only as polar cases. Moreover, we show that separation and pooling may affect the allocative efficiency of the procurement in a counterintuitive way, such that a less bunching mechanism can be a more inefficient one.
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