doi:10.1136/bmj.324.7337.606 2002;324;606-607 BMJ J Martin Bland and Douglas G Altman Statistics Notes: Validating scales and indexes http://bmj.com/cgi/content/full/324/7337/606 Updated information and services can be found at: These include: Rapid responses http://bmj.com/cgi/eletter-submit/324/7337/606 You can respond to this article at: service Email alerting the top right corner of the article Receive free email alerts when new articles cite this article - sign up in the box at Topic collections (490 articles) Other Statistics and Research Methods: descriptions • Articles on similar topics can be found in the following collections Notes http://www.bmjjournals.com/cgi/reprintform To order reprints of this article go to: http://bmj.bmjjournals.com/subscriptions/subscribe.shtml go to: BMJ To subscribe to on 20 March 2005 bmj.com Downloaded from