HEALTH SYSTEM is a broad field. The use of six sigma in medical science and/or health fields in certain procedures could not be relaxed, i.e. medical procedure, medical devices, artificial organs, etc. The 6 sigma assures high quality and zero tolerance for error- - - - at least as an ideal to limit error to minimal.
HEALTH SYSTEM MANAGEMENT may be lowered to more acceptable level where error may be 2% - 5%, so long as it does not lead to compromising safety or poses serious threat to human life. For example, applying 95% in facility management, accounting, resource management, etc.
Six Sigma is a methodology... scientific way to validate changes (improvements) you need data and analyze them, if you don´t have data, u have to get it, once you have a statistical solution you go for the real solution, here is the problem, when you try to improve the process, and the process are managed by humans, and as "normal" thy have his "shape" so, is not easy to "move" the "average" or reduce the "variance"