> Are you saying the assumption that the curve will change significantly is questionable or that the effects of the assumed change in the curve change are immat

> Are you saying the assumption that the curve will change significantly is questionable or that the effects of the assumed change in the curve change are immaterial? Sorry, that's not quite what I am saying. My point was that "given the purpose of this analysis, mortality factors are immaterial." If the purpose of this analysis was to give some quantitative answers that were going to be used as the basis for decisions - then it's highly likely that you would want to build in mortality improvement. However, in this case the analysis is just a simple illustration to convey a simple idea (actual lifespan vs life expectancy), and I would say that building in mortality improvement would muddy the waters and make it just that little bit harder for the audience to understand.