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Table 1 Categories for confirming and excluding power, and the corresponding effect on moving toward a higher or lower post-test probability on the log10 odds scale

From: Rational use of Xpert testing in patients with presumptive TB: clinicians should be encouraged to use the test-treat threshold

Power of the argumenta Strength Steps on the scaleb
100 (58–200) Very strong 2
33 (17 to 57) Strong 1.5
10 (6 to 16) Good 1
3 (2 to 5) Weak 0.5
1 Useless 0
  1. aConfirming or excluding power can range between 1 and infinity. However, power is rarely 1000 or more
  2. bIf confirming power, add the respective number of steps, if excluding power, subtract steps (unit in log10 odds)