That study is great for illustrating how deceptive percentage of variance explained statistics can be. They terminated this study prematurely because the early returns showed an effect so large (odds ratio of about 1.8) that it was deemed unethical to continue the study. In terms of variance explained, the treatment accounted for about one tenth of one percent of the variance in MI.
Cheers, [Karl L. Wuensch]<http://core.ecu.edu/psyc/wuenschk/klw.htm> From: John Kulig [mailto:[email protected]] Sent: Tuesday, January 15, 2013 3:39 PM To: Teaching in the Psychological Sciences (TIPS) Subject: Re: [tips] Flu vaccine and p.6 level of significance Nice replies (Jim C, Karl W and Mike P and others ..) so I won't repeat what has been said except to note - as a tangent to the original posts - that in some of my classes I spend time with the "relative risk" Karl W discusses. I use the example of aspirin and MI (heart attack) in the 1988 (New England Journal of Med?? if I remember) article of 22,000+ physicians who took aspirin vs. placebo. My chi square calculated on their frequencies reveal p < .01, yet the risk of MI only drops from 1.7% to .9% in the sample over the years studied. As an absolute value, the % decrease is very small, but expressed as relative risk we can say we cut the risk in half. Of course, any "significant" decrease will be championed as the stakes are very high with MI .. and sometimes high with flu as well .. At any rate, I got MY flu shot! So I am OK. p < .05 :-) ========================== John W. Kulig, Ph.D. Professor of Psychology Coordinator, University Honors Plymouth State University Plymouth NH 03264 ========================== --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=23047 or send a blank email to leave-23047-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
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