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There were several comments made by respondents (most of whom are apparently on this list), that I would like to respond to. Comment: The statistical proof is not available in another way. I am no expert but can't we demonstrate that something is helpful just by a larger sample size or is a control group always required? Can't we pair people as close as possible and not have sham? Response: A basic principle in statistics is that a larger sample size does not correct for bias. For example, in the classic case, if the investigators are emotionally committed to showing that the treatment works, and if they know which patients got the new treatment, they will have an unconscious tendency to evaluate patients in the treated group differently from those in the controls. This is particularly true with diseases like PD, where the evaluation is not strictly objective. It is also a problem using "historical controls" or pairing patients as suggested by the commenter, since the evaluations of the treated group would be subject to evaluation bias. This is separate from the "placebo effect", where patients getting a placebo actually do better than they would otherwise. Comment: There are alternatives to double blind trials, they are actually becoming quite common for diseases like cancer where it would be unethical to give a patient a placebo and let the patient die to prove that a new medication is effective. The studies aren't as simple, but these could and should be applied to Parkinson's surgeries as well. Response: Standard practice for trials involving serious diseases is to give the control group whatever the current standard treatment is for that disease. The object is not to prove that the new treatment is better than nothing but that it is better (or not) than the current standard practice. In the simplest case, where both treatments are pills, the treated group will get two sets of pills, one of which is the new drug and one a placebo, while the control group also gets two sets of pills, one of which is the placebo and and one the standard treatment. The total treatment of each of the groups looks the same as the other one. That way, the patients in the control group get the same treatment as they would have if they were not in the trial. ----- Original Message ----- From: "[log in to unmask]" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, September 07, 2007 7:11 PM Subject: Opinions on the use of sham surgery in PD research Over the last month, some listmembers participated in the Parkinson Pipeline Project's " Opinion Survey on Sham Surgery in Parkinson's Clinical Research." The results are now in. The results of the opinion poll and respondents' comments are on the PPP website at: http://www.pdpipeline.org/whatsnew/shamsur_survey.htm There is also a link from the homepage www.pdpipeline.org Thanks to everyone who participated. Linda Herman ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn