Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2015 Jan;55(1):58-64.
doi: 10.1177/0025802414524385. Epub 2014 Mar 18.

Alcohol calculations and their uncertainty

John Searle  1
Affiliations

Alcohol calculations and their uncertainty

John Searle. Med Sci Law. 2015 Jan.

Erratum in

  • Erratum.
    [No authors listed] [No authors listed] Med Sci Law. 2015 Apr;55(2):145. doi: 10.1177/0025802415585926. Med Sci Law. 2015. PMID: 25977508 Free PMC article.

Abstract

A dilution model is widely used to link blood alcohol concentration and the quantity of alcohol consumed. Whilst some authors use the total body water formulation of that model, others use the Widmark Factor formulation. A paper by Forrest gave a table of example values of the Widmark Factor and Barbour, based on Forrest's work and using Forrest's computer program, subsequently presented Forrest's results by way of a chart. Whilst the results of Forrest and Barbour are often used interchangeably, there is a significant difference between them on the factors for women. This paper examines the source of the unexpected discrepancy. It is essential to quote an error range, in blood alcohol concentration calculations, for the results. The extent of that error range was investigated by Gullberg who also employed the Widmark Factor formulation. Gullberg concluded that when reporting a calculated blood alcohol concentration, a coefficient of variation of ± 21% should be applied. Similarly, Gullberg concluded that when calculating the volume of drink, a coefficient of variation of 12½ % should be applied. The present paper derives and publishes the formulae for calculating this coefficient of variation. It is then shown that Gullberg's conclusions are mistaken: the coefficient of variation is not some fixed percentage but must be calculated in each case.

Keywords: Widmark; alcohol; calculations; error; uncertainty.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Barbour’s and Forrest’s results for the Widmark Factor. Note: BMI = Weight in kilograms/Square of height in metres.
See this image and copyright information in PMC

Comment in

References

    1. Widmark EMP. Principles and applications of medicolegal alcohol determination. English translation of 1932 German edition, Davis Biomedical Publications 1981.
    1. Zuba D and Piekoszewsk W. Uncertainty in theoretical calculations of alcohol concentration. In: Proc. 17th Internat. Conf. on Alcohol, Drugs and Traffic Safety, Glasgow, 2004.
    1. Watson PE, Watson ID, Batt RD. Predictions of blood alcohol concentration in human subjects. J Studies Alcohol 1981; 42: 547–556. - PubMed
    1. Forrest ARW. The estimation of Widmark’s Factor. J Forensic Sci Soc 1986; 26: 249–252. - PubMed
    1. Gullberg RG. Estimating the uncertainty associated with Widmark’s equation as commonly applied in forensic toxicology. Forensic Sci Int 2007; 172: 33–39. - PubMed

LinkOut - more resources