Shelling (1960) among others have argued that contributions to public goods may be larger if people spread their contributions and give one small contribution at a time. Examining a threshold public good environment, Marx and Matthews (2000) show that multiple rounds may secure a provision level...

This paper tests the robustness of the "two-tiered market" in which efficient bilateral contracts emerge between firms and workers (Brown, Falk and Fehr, 2004). Our experiment introduces stochastic interruptions in firms' ability to offer contracts. Involuntarily laid off workers are eager to be...