How full is the glass?

doi:10.1136/bmj.39520.483565.3A

BMJ 2008;336:629-630 (22 March), doi:10.1136/bmj.39520.483565.3A

Letters

Moving beyond depression

How full is the glass?

The first 150 words of the full text of this article appear below.

Instead of speculating about our differing methods as the sourceof our differing conclusions, Turner and Rosenthal instead focusedon our adoption of UK’s National Institute for Healthand Clinical Excellence (NICE) criteria for clinical significance.NICE adopted Cohen’s definition of a "medium" effect size(0.5) for clinical significance.¹ ² Cohen intended that a mediumeffect size represent an effect of a size likely to be visibleto the naked eye of a careful observer (p 156). By this interpretation,clinical significance of antidepressants is reached when a carefulobserver can see that medicated patients have noticeably lowerdepression than patients taking placebo. In this light, theNICE criteria seem sensible indeed.

A more appropriate use of Turner and Rosenthal’s "d-juice"metaphor (where d-juice is the level of antidepressant efficacy)to explain our findings is that the amount of d-juice in thetrials was pitifully small or even non-existent when people. . . [Full text of this article]

Irving Kirsch, professor of psychology, Blair T Johnson, professor of psychology

¹ University of Hull, Hull HU6 7RX, ² Department of Psychology and Center for Health, Intervention, and Prevention, University of Connecticut, Storrs, Connecticut, USA

I.Kirsch@hull.ac.uk