The participation decision versus the level of participation in an environmental treaty: a spatial probit analysis

This paper represents treaty participation as a two-stage game, for which nations first decide whether or not to participate and then they choose their level of participation. The resulting subgame perfect equilibrium is used to derive a reduced-form equation for estimating and separating the influences of the variables at the two decision stages. This spatial probit equation forms the basis for a full-information maximum likelihood estimator that accounts for the simultaneity bias associated with public good spillins at both stages. When the procedure is applied to the Helsinki Protocol, we find that the strategic influence of a variable may drastically differ depending upon which stage is scrutinized.