Cooperation and Noise in Public Goods Experiments: Applying the Contribution Function Approach
We introduce a new design for experiments with the voluntary contributions mechanism for public goods. Subjects report a complete contribution function in each period, i.e., a contribution level for various marginal rates of transformation between a public and a private good. The results show that subjects' behavior cannot be explained exclusively as the result of errors. Individuals exhibit essentially one of two types of behavior. One group of subjects behaves in a way, consistent with some kind of other-regarding motivation. Some features of the data indicate that these subjects' behavior is interdependent. Another group of subjects behaves in accordance with a utility function that depends only on their own earnings. The interaction between these two groups may be important when explaining behavior over time.