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 Table of Contents    
Year : 2017  |  Volume : 59  |  Issue : 2  |  Page : 248
Age is a number, not a group

Department of Psychopharmacology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India

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Date of Web Publication17-Jul-2017

How to cite this article:
Andrade C. Age is a number, not a group. Indian J Psychiatry 2017;59:248

How to cite this URL:
Andrade C. Age is a number, not a group. Indian J Psychiatry [serial online] 2017 [cited 2020 Jul 14];59:248. Available from:


The July–September 2016 issue of the Indian J Psychiatry carried eight original articles. Of these, one [1] provided only a range of values for the age of the participants, and another [2] provided no description of the sample, at all. These are serious limitations of a manuscript because, without descriptive information about the sample, readers cannot know to what population the results of a study may be generalized.

Three other papers [3],[4],[5] presented data on age not as mean (standard deviation) values, but in class intervals or groups that were otherwise defined. This is completely illogical; age is a number, not a group. When continuous variables are categorized, precision is lost, and the ability of inferential statistical tests to identify statistical relationships is weakened. Continuous variables should be categorized only if there is a specific need, such as for administrative purposes, or when the data could not be accurately recorded, or when the distribution is skewed.[6],[7]

Similar considerations apply to other continuous variables, as well; for example, education can be operationalized in units of years rather than as specific levels of attainment as presented by at least two teams of authors.[3],[5]

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Conflicts of interest

There are no conflicts of interest.

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Andrade C. Categorizing continuous variables. Can J Psychiatry 2002;47:35.  Back to cited text no. 7

Correspondence Address:
Chittaranjan Andrade
Department of Psychopharmacology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/psychiatry.IndianJPsychiatry_99_17

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