The end of REFVAL

The statistical program RefVal has had an exceptionally long lifespan — more than 30 years! — but now it has approached its final phase.

As the chairman of the Expert Panel on Theory of Reference Values of the International Federation of Clinical Chemistry (IFCC) in the period 1979–1987, I was responsible for the preparation of the international recommendation on the statistical treatment of reference values [1]. During the development of this document, it was necessary to test out the proposed statistical methods on real data. Therefore, I wrote a Fortran program for this purpose. Since some of the algorithms described in the final version of the recommendation were not included in general statistical program packages, I decided to modify somewhat my program and make it available to the scientific community under the name RefVal. The first version, still a Fortran program, was released in 1983. Since then it has been revised several times. From 1986 it has been a Pascal-based program, at first for MS-DOS, and since 2001 for Windows. The latest release (version 4.11) was made available in 2006. Since then no bugs have been reported, and the program source code has not been touched.

RefVal has always been and still is a program that implements the international recommendation on the statistical treatment of reference values [1]. A description of the program has been published [2]. The only major addition to the algorithms described in the IFCC document is a modified Horn’s method for detection of outliers [3], which was added in 2005.

During all these years, RefVal has been distributed to numerous scientists on all continents. Several of my customers have also asked for help and guidance for the statistical treatment of reference values and for the application of the algorithms included in RefVal.

However, I realize that — at an high age and several years of retirement — I have now come to a point where my commitment to RefVal and my guiding activities should finish. Without contact with the scientific community and no reading of relevant literature, I am certainly not aware of the current status neither of the theory of reference values nor of their statistical treatment.

The history of RefVal has come to an end !

I shall therefore not maintain the RefVal program any more, new features shall not be added to it, I shall not support its users, and I cannot take the responsibility of giving scientific counseling.

Nevertheless, the RefVal program (version 4.11) is still available for those want to use it. If the methods described in the IFCC recommendation [1] suit your requirements, you may contact me for a copy of the program. For the service I shall charge 500 Norwegian Crowns (NOK, or equivalent in foreign currency), that is, approximately one third of the previous price. The program and supporting files, including a user’s guide, will only be distributed by file transfer through Internet (FTP).

Order and payment information:

Helge Erik SOLBERG, Elmholt allé 13, N-0275 OSLO, Norway,

Payment only by bank transfer to the RefVal account. IBAN number: NO4997105191875, SWIFT/BIC-code: DNBANOKK

Addition September 27, 2016: The RefVal program, both the source code and the executable program, has now been made available in the public domain. Free download:



[1]     Solberg HE, Ed. (IFCC). Approved recommendation (1987) on the theory of reference values. Part 5. Statistical treatment of collected reference values. Determination of reference limits. J. Clin. Chem. Clin. Biochem. 25, 645-656, 1987; Clin. Chim. Acta 170, S13-S32 1987.

[2]     Solberg HE. RefVal: a program implementing the recommendations of the International Federation of Clinical Chemistry on the statistical treatment of reference values. Comput. Meth. Progr. Biomed. 48, 247-256, 1995.

[3]     Solberg HE, Lahti A. Detection of outliers in reference distributions: performance of Horn’s algorithm. Clin. Chem. 2005; 51: 2326–2332.

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