This paper develops a correlated probit model to describe dichotomous choices that may contain a public-goods component or some other forms of interdependency. The key contribution of the paper is to formulate tests for interdependent behavior among agents. In particular, we examine the decisions by nations whether or not to ratify the Montreal Protocol on Substances that Deplete the Ozone Layer. Specifically, we reject free riding as a motive for not ratifying the Protocol, and we find little evidence that individual nations were influenced by the behavior of their largest trading partners. Hence, the data suggest that, with respect to the Montreal Protocol, most nations acted without regard for the actions of other nations.

This paper uses three different approaches to investigate whether the declining provision of public capital is a major cause of declining labor productivity. The juxtaposition of approaches removes the variability in estimates due to dissimilar variable definitions and econometric methodologies. Estimates are based on U.S. time-series data and are evaluated by the implied elasticities of substitution, the prediction of labor productivity trends, and the impact of public capital on productivity. As the three approaches yield very different estimates, it will be hard to ever settle the debate about the effect of public capital on private productivity.