All of this might be relevant in a conversation between accountants or investment analysts, but it's pretty obvious the "study" chose this particular methodology to get a number that makes insurance companies look as bad as possible. In this context, using their methodology does more to obfuscate/mislead than to clarify. If you say that UHI has a profit margin of 15%, most people would interpret that to mean that per $1000 worth of premiums paid, they make $150, which is exactly what happens. Their argument of "they charge $1000 in premiums, but of that $800 is paid out as costs, therefore their margin is 75%" is more confusing.