Research Article Statistics at square one. XX-Correlation (concluded). Br Med J 1976; 2 doi: https://doi.org/10.1136/bmj.2.6039.802 (Published 02 October 1976) Cite this as: Br Med J 1976;2:802 Article Related content Metrics Responses Peer review This article has a correction. Please see:Medical M.P - July 18, 1970 This is a PDF-only article. The first page of the PDF of this article appears below.