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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)