The gunslinger fallacy

[StuW]

Hmm I saw something like this a few weeks back. My JW brother-in-law posted an article on Facebook about evidence that JW's who refuse a blood transfusion heal faster and with less complications than non JW's who do have transfusions. After shaking my head and facepalming a little I did some digging and found the original paper which had some interesting details. The numbers of participants was 322 JW's vs 87,543 non-JW's and the article also neglected to mention the footnote in the paper saying that any surgeon knowing the patient would refuse a transfusion would only consent to the procedure for the patients most likely to have less complications, thereby skewing the results considerably.

Edit: here's the abstract if anyone is interested.
http://www.ncbi.nlm.nih.gov/pubmed/22751620