One of the most influential and impressive reports against the idea that treaties retain a special political purpose and that they may in fact be inferior to the executive agreement of Congress is provided by Oona Hathaway. 107 Michael Waibel, Fair and Equitable Treatment as Boilerplate (not yet published, 2018). A second limitation of this study is that, although it suggests that treaties retain their value as a policy tool, it does not directly address the relative importance of the various assumptions for greater contract sustainability. Several mechanisms have been proposed that could explain this sustainability, from signal theory to the stability of Senate preferences to the possibility that the consultation and consent process will reveal more credible information to negotiators. Of course, none of these explanations are mutually exclusive; In fact, it may be naïve to assume that a single theory can explain the choice between engagement arrangements for each agreement. However, since all the mechanisms in this analysis lead to equivalent results in terms of observation, the results provide little guidance to those who wish to assess and compare the relative importance of each of the proposed explanations. As explained in the text, survival times are continuous in nature, as international agreements can expire at any time. However, since survival times are only measured once a year when the FIT is published, the data can be described as continuous data aggregated by year. For truly continuous data where an event can occur at any time, cox`s proportional risk modelFootnote 117 has emerged as the preferred choice for researchers, footnote 118, as it is a semiparametric model based on only a few assumptions. The popularity of this model stems from the fact that it can be estimated without making parametric assumptions about the reference hazard rate.

For example, the researcher does not have to assume that survivability will decrease over time, exponentially, or in other predefined ways at a constant rate. However, Cox`s model assumes that there are no links in the data, which means that no two observations have exactly the same survival time. This is because links cannot occur when survival times are measured on a truly continuous scale. The researchers have developed several techniques that make the Cox model manageable even with bonds. The most accurate approach is the “exact method” developed by Veal and Prentice. Footnote 119 Intuitively, the exact method when two subjects i and k survive exactly n periods, the alternative I survived longer than k and the alternative that k survived longer than i and opts for the one that is most likely. Footnote 120 However, in documents covering many topics, periods and connections, the exact method is not feasible because it requires a lot of calculations. .