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Rajendra Persaud, MSc, MPhil, MD, MRCPsych
Croyden Mental Health Services Warlingham Park Hospital London, England

Arch Gen Psychiatry. 1996;53(12):1165.

	Since this article does not have an abstract, we have provided the first 150 words of the full text PDF and any section headings.

In the September 1995 issue of the Archives, Elkis et al¹ conclude their meta-analysis of ventricular enlargement in patients with mood disorders with the statement that the statistical power of meta-analysis has allowed them to uncover significant evidence for a greater degree of ventricular enlargement in patients with schizophrenia compared with patients with mood disorders.

However, their emphasis on the small P value associated with the finding may be misplaced, as they neglect to discuss in detail the associated importance of their fail-safe N=10 value for their comparison of 11 studies, which were pooled to provide an effect size of 0.2.

It may be worth recalling the importance of the failsafe N statistic given that Elkis et al actually calculate this value but then fail to fully interpret it. The fail-safe N may be defined as the number of new, unpublished or unretrieved, nonsignificant "null-result" studies that, on average, . . . [Full Text PDF of this Article]

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