A blinded experiment is one where some of the persons involved are prevented from knowing certain information that might lead to conscious or unconscious bias on their part, invalidating the results.
For example, when asking consumers to compare the tastes of different brands of a product, the identities of the brands should be concealed — otherwise consumers will generally tend to prefer the brand they are familiar with. Similarly, when evaluating the effectiveness of a medical drug, both the patients and the doctors who administer the drug may be kept in the dark about the dosage being applied in each case — to forestall any chance of a placebo effect, observer bias, or conscious deception.
Blind experiments are an important tool of the scientific method, in many fields of research — from medicine, forensics, psychology and the social sciences, to basic sciences such as physics and biology and to market research. In some disciplines, such as drug testing, blind experiments are considered essential.
In case no one noticed, the above is a quote edited down from the usual
source. I did not add quotation marks to hopefully avoid any preconceived notions about what was written.
I can understand beeman's objections to some of the anti-cabler's proposed blind tests. Such as the one where the tester tells the subject that the cables are being changed, but really they are not. This would be a single-blind test, where the tester might still exert his or her bias over the subject.
A proper double-blind test would have the testers equally in the dark about the cables being swapped. Maybe the new cable is identical to the previous one, or maybe it is a completely different design. But neither party will know until the experiment is over and the wrapping around the cables is removed. In fact, the testers can even be selected from a group of pro-cablers and it should not make a difference. That seems like a fair test to me.
