Why is Double Blind Testing Controversial?


I noticed that the concept of "double blind testing" of cables is a controversial topic. Why? A/B switching seems like the only definitive way of determining how one cable compares to another, or any other component such as speakers, for example. While A/B testing (and particularly double blind testing, where you don't know which cable is A or B) does not show the long term listenability of a cable or other component, it does show the specific and immediate differences between the two. It shows the differences, if at all, how slight they are, how important, etc. It seems obvious that without knowing which cable you are listening to, you eliminate bias and preconceived notions as well. So, why is this a controversial notion?
moto_man
Onhwy61 -- it is specifically the motivations that yield the controversy. A DBT could, with great effort, be designed to yield reasonably valid results. The posts above suggest that such effort is seldom made because the test sponsors don't understand or believe that effort is required. Without going through all that work, the test becomes a "double deaf test" as Unsound suggests.
A true double blind test wouldn't be easy to set up, but as a scientific experiment it really isn't very hard. As far as interpreting the results of an experiment goes, I don't think you can design an experiment that isn't open to misinterpretation. It's a very different statement and attitude to say that a DBT has to be well designed and rigorous than to say DBTs serve no useful purpose.
I have a proposal ... double blind posting. Audiogon allows us to post our views with anonymity. Other Agoners then guess who posted which post, according to the content of the post, and the (extreme) opinions therein.
Suggestions for starter threads : "Power cords make no difference" and "SACD is killing digital".
This is a very important proposal and needs urgent consideration - and should not be treated flippantly Sean. I for one am very concerned that readers of posts are likely to be biased against individual posters - for example, had I a prejudice against the Irish I may very well have not taken the last post as seriously as it deserves. The danger if we do not have double blind posting - and I believe posts should be scattered randomly about the site, just to be sure - then readers will not get the true meaning of what is posted here, as they will read with tinged spectacles.
To address Sean's and other's points about pulling random folks in off the street for DBTs, you are quite correct. You can't just grab someone off the street, put the music on and test away. In truly valid tests - and these are in the minority, I suspect - there is a training component. During this time, if I recall correctly, some screening is also done.

The best candidates for DBTs may be well-trained 10-year-olds!