Models vs. Experts #10: Lung Function tests

Models vs. Experts #10: Lung Function tests

August 7, 2013 Behavioral Finance, Uncategorized
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(Last Updated On: January 18, 2017)

Comparison of reports on lung function tests made by chest physicians with those made by a simple computer program

  • Geddes, D. M., Green, M., & Emerson, P. A.
  • Thorax, 33, 257-260
  • An online version of the paper can be found here
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The numerical results of 60 sets of pulmonary function tests were submitted to five consultant chest physicians for independent reporting. The chest physicians’ reports were compared with the reports generated by the on-line computer reporting system in routine use in the pulmonary function laboratory at Westminster Hospital. There was good agreement between the reports of the chest physicians among themselves and with the computer. The individual reports were compared with the consensus opinions of the physicians and the computer. The computer’s decisions differed from the consensus opinion in 4.6% of instances. The comparable figures for the five physicians were respectively 2.9%, 2.9%, 2.9%, 4.0%, and 4.6%. Decisions differing from the consensus were due to mistakes or actual sustained disagreements of opinion. The physicians made more mistakes than the computer even though they were performing under test conditions. They made up for this, however, by producing fewer genuine disagreements from the consensus opinions. It is concluded that in routine day-to-day practice the computer report will be as consistently useful as the chest physicians’ reports and more immediately available.


The authors compare the interpretive reports of a simple computer algorithm and experienced chest physicians on the same set of raw test results from lung function tests.

Here is how the test works (my layman interpretation)

  1. Patients breath in and out of a tube under different test conditions and the computer tabulates all the raw results.
  2. 60 patients are analyzed.
  3. The results are given to a group of 5 chest doctors and a computer.

Here are the results from the test. Note, “mistake” for a computer is due to incorrect entry of data or copying of the report from the the display to the form.

  • Mistakes by the computer are lower.
  • Disagreements from consensus are higher for the computer.


On net, the computer and the doctors are pretty similar. Of course, the computer is much cheaper, more efficient, and won’t call in sick when their buddy invites them to a golf game (I’ve pulled that one before 😉 ).

Thoughts on the paper?

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About the Author

Wesley R. Gray, Ph.D.

After serving as a Captain in the United States Marine Corps, Dr. Gray earned a PhD, and worked as a finance professor at Drexel University. Dr. Gray’s interest in bridging the research gap between academia and industry led him to found Alpha Architect, an asset management that delivers affordable active exposures for tax-sensitive investors. Dr. Gray has published four books and a number of academic articles. Wes is a regular contributor to multiple industry outlets, to include the following: Wall Street Journal, Forbes,, and the CFA Institute. Dr. Gray earned an MBA and a PhD in finance from the University of Chicago and graduated magna cum laude with a BS from The Wharton School of the University of Pennsylvania.