Check out Annual Reports 2011 and 2012 for starters. The Chairman and CEO reports on what were known factors at the time are particularly interesting with the advantage of hindsight. It seems to me that the shapeshifting US Healthcare system and associated regulatory quagmire are PEB's biggest problem. Now that Congress are trying to unfund AHRQ does this open another can of worms elsewhere? These barriers were noted as possible regulatory risks in the reports but I think they may have underestimated the possible effects and therefore the delays. There was a chart, which I can no longer find, regarding the estimated market penetration which showed a 10 percent MP raising 100 mill GR anually in the 5th year. Someone may be able to help.
Regardless, PEB did a lot of homework on this and based their projections on known factors at the time.
What else would you use?
They definitely did not just pluck it out of the sky and there are plenty of warnings to all concerned that there are risks involved in many areas, some unknown.