Recently, there was an extensive discussion about how to analyze data involving marijuana use and heart attacks. I just came across an interesting study that shows how to do a rigorous analysis in a very similar situation, the risk of heart attacks after sex. The actual paper appears in JAMA, but there is an excellent summary of it on the Bandolier web site: http://www.jr2.ox.ac.uk/bandolier/band30/b30-2.html This is a fun teaching example. Steve Simon, [EMAIL PROTECTED], Standard Disclaimer. STATS: STeve's Attempt to Teach Statistics. http://www.cmh.edu/stats Watch for a change in servers. On or around June 2001, this page will move to http://www.childrens-mercy.org/stats ================================================================= Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =================================================================