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Antidepressant Benefits: Misinference from ordinal scales?

Posted by plosmedicine on 31 Mar 2009 at 00:24 GMT

Author: Peter Tennant
Position: Biostatistician
Institution: Newcastle upon Tyne
Submitted Date: March 19, 2008
Published Date: March 25, 2008
This comment was originally posted as a “Reader Response” on the publication date indicated above. All Reader Responses are now available as comments.

Further to the comment made by Turner (‘Parallel discussion going on at’) there are also a number of posts responding to the BMJ news item 'Meta-analysis shows difference between antidepressants and placebo is only significant in severe depression' (

I would particularly recommend that readers acquaint themselves with the response written by myself and Tennant entitled 'Antidepressant Benefits: Misinference from ordinal scales?' ( In this, we raise concerns about the use of meta-regression, which assumes equal interval scaling, considering the data do not satisfy this condition.

No competing interests declared.