How to Obtain NNT from Cohen's d: Comparison of Two Methods

Toshi A. Furukawa; Stefan Leucht

doi:10.1371/journal.pone.0019070

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Open Access

Peer-reviewed

Research Article

How to Obtain NNT from Cohen's d: Comparison of Two Methods

Toshi A. Furukawa ,

* E-mail: furukawa@kuhp.kyoto-u.ac.jp

Affiliation Department of Health Promotion and Human Behavior (Cognitive-Behavioral Medicine), Kyoto University Graduate School of Medicine/School of Public Health, Kyoto, Japan
⨯
Stefan Leucht

Affiliation Department of Psychiatry and Psychotherapy, Technische Universität München, Klinikum rechts der Isar, Munich, Germany
⨯

How to Obtain NNT from Cohen's d: Comparison of Two Methods

Toshi A. Furukawa,
Stefan Leucht

Published: April 27, 2011
https://doi.org/10.1371/journal.pone.0019070

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Error in Furukawa NNT formula

Posted by richarddmorey on 17 Feb 2016 at 18:54 GMT

I believe there is a typo in the Furukawa NNT formula. It should be "d +" rather than "d -". It is easy to see it must be wrong because d=0 must lead to NNT=Inf. The equation as it stands will not give the correct answer unless CER is 50%.

No competing interests declared.

RE: Error in Furukawa NNT formula

tschkfrkw replied to richarddmorey on 18 Feb 2016 at 02:16 GMT

Thank you very much for pointing this out. Yes, it was a typo and it should be "d + " and not "d -" in the top left formula on page 2. (Toshi A. Furukawa)

No competing interests declared.

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How to Obtain NNT from Cohen's d: Comparison of Two Methods

How to Obtain NNT from Cohen's d: Comparison of Two Methods

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Error in Furukawa NNT formula

Posted by richarddmorey on 17 Feb 2016 at 18:54 GMT

RE: Error in Furukawa NNT formula

tschkfrkw replied to richarddmorey on 18 Feb 2016 at 02:16 GMT