See Zulip chat:

https://chat.fhir.org/#narrow/stream/103-Orders-and.20Observation.20WG/subject/ReferenceRange.20value.20set.20-.20type.2Fmeaning

ref range valueset definition of normal is too strict propose changing it from:

http://build.fhir.org/valueset-referencerange-meaning.html

From

"Within two standard deviations from the mean and accounting for 95.45% of the relevant control population."

To

"Values expected for a member of the relevant control population being measured. Typically each results producer such as a laboratory has specific normal ranges and they are usually defined as within two standard deviations from the mean and account for 95.45% of this population."