To put the "50% chance of survival" in perspective (and I don't get the feeling that the posters here are interested in perspective), that quote comes from page 7 of a 10 page report. It is preceded by the words "If pushed to speculate,.....". I found it to be an interesting analysis, and as I said in an earlier post, it outlines the many variables and how they may influence what came down to the much quoted 50% statement.