In each model specification, the coefficient on the contractual indicator is negative and is significantly different from zero. Note that coefficients in survival models change the probability of an event, i.e. The danger rate, express it. Here, the event is defined as an agreement that ends. Therefore, a negative coefficient indicates a decrease in the likelihood that an agreement will be cancelled if it is concluded in the form of a treaty. The results imply that contracts take much longer than executive agreements and that the difference in sustainability is not the result of arbitrary factual conventions or a by-product of a decision-making process determined primarily by the Senate seat card. Before continuing the analysis, it is important to address any limitations to this data set. . .