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
. 2003 Sep 27;327(7417):741-4.
doi: 10.1136/bmj.327.7417.741.

Simple tools for understanding risks: from innumeracy to insight

Gerd Gigerenzer  1 , Adrian Edwards
Affiliations

Simple tools for understanding risks: from innumeracy to insight

Gerd Gigerenzer et al. BMJ. .

Abstract

Bad presentation of medical statistics such as the risks associated with a particular intervention can lead to patients making poor decisions on treatment. Particularly confusing are single event probabilities, conditional probabilities (such as sensitivity and specificity), and relative risks. How can doctors improve the presentation of statistical information so that patients can make well informed decisions?

PubMed Disclaimer

Figures

Fig 1
Fig 1
Doctors' estimates of the probability of breast cancer in women with a positive result on mammography, according to whether the doctors were given the statistical information as conditional probabilities or natural frequencies (each point represents one doctor)
Fig 2
Fig 2
Different representations of the same benefits of treatment: the reduction after treatment in the number of people who have a stroke or major bleeding looks much larger on the left, where the reference class of 100 patients who have not had a stroke or bleeding is not shown
See this image and copyright information in PMC

Comment in

References

    1. Hoffrage U, Gigerenzer G. Using natural frequencies to improve diagnostic inferences. Acad Med 1998;73: 538-40. - PubMed
    1. Gigerenzer G. Reckoning with risk: learning to live with uncertainty. London: Penguin, 2002. (Published in the United States as Calculated risks: how to know when numbers deceive you. New York: Simon & Schuster, 2002.)
    1. Slaytor EK, Ward JE. How risks of breast cancer and benefits of screening are communicated to women: analysis of 58 pamphlets. BMJ 1998;317: 263-4. - PMC - PubMed
    1. Casscells W, Schoenberger A, Grayboys T. Interpretation by physicians of clinical laboratory results. N Engl J Med 1978;299: 999-1000. - PubMed
    1. Gigerenzer G, Hoffrage U. How to improve Bayesian reasoning without instruction: frequency formats. Psych Rev 1995;102: 684-704.

Publication types