Percentiles as reference values for laboratory data.

It has been suggested that laboratory results be reported, not only in conventional units, but also in terms of equivalent percentiles from a reference population. This would afford the clinician an easily interpretable measure of how unusual such a result would be in the reference population. This paper describes a modified method for estimation of reference percentiles. This method does not require any assumption about the distribution of the reference population, but it has a smaller variability than that from earlier methods based on interpolation. This method is now being used to furnish percentile values for spirometric data in the authors' laboratory.