Table 5.3Likelihood of Abnormal Tests, by Chance Alone, on Large Multiple-Test Batteries

Number of tests in batteryLikelihood of at least one test abnormal by chancea
15%
210
314
419
523
1040
2064
4087
a

Assumes normal range chosen as ± 2 standard deviations from mean to normal population.

From: Chapter 5, Use of the Laboratory

Cover of Clinical Methods
Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.
Walker HK, Hall WD, Hurst JW, editors.
Boston: Butterworths; 1990.
Copyright © 1990, Butterworth Publishers, a division of Reed Publishing.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.