Talk:Blind experiment

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Does anyone know who carried out the first true double blind trial and thus invented the methodology?

Noel jackson. LIFE.Newcastle

  • Suggest merging Blinding (medicine) into this topic. I also want to add references to the scientific method, social sciences, psychology, and the physical sciences. Blinding is not just important in medical clinical trials, its important in all sciences. I had considered creating a topic Blinding (scientific method) and merging both into it, but Double-blind is already a pretty good topic and its the term most people would use when searching for information. Thatcher131 07:53, 11 February 2006 (UTC)
  • I did a rewrite incorporating the medical-specific material from Blinding (medicine) in preparation to an official merge. I added a bit about single-blinded studies which is redundant to the single blind entry but I think its useful to have it here in case someone comes from a link and doesn't know what blinded research is. I also wrote it generically to cover all research as blinding is not important just in medical research. I added one non-medical example and would love to see more non-medical examples. Thatcher131 04:45, 12 February 2006 (UTC)

Contents

[edit] Placebo & mice

For the risk of being laughed at. Is there any proof that mice experiments are not influenced by placebo effect. I can imagine the lab staff talking to the doomed mice "here you buggers, eat this, you will all die soon anyhow." and to the lucky mice "look over to you neighbors, they're gonna die soon, you are the lucky ones". And maybe the mice understand ? If not word for word, but maybe body language.

Is double blind method being used with mice experiments ?

-- Paparodo, dec 13th 2006 —The preceding unsigned comment was added by 217.10.60.85 (talk) 11:46, 13 December 2006 (UTC).

[edit] Double placebo numbers

Does anyone know if there was a double-blind study where BOTH groups were given a placebo, but both were told that one group was getting a med and one was not? Did anyone measure what is the % of success of placebo group that is always reported by a placebo group in a double-blind study.

What I am looking for is a percent of success reported from the placebo group?

Was there such study?

Can someone post that?

Thanks.

Atessitore05 13:50, 13 December 2006 (UTC)

I doubt there's any single number. Successful outcomes in either group (control and test) can potentially range anywhere from none to all. Given the variety of therapies being tested, and the conditions being studied, would you expect success to even be defined the same way, much less measured at a consistent rate? At any rate, the article on the placebo effect is probably a good place for you to look for more information. In fact I found this there: "...studies generally do not include an untreated group, so determining the actual size of the placebo effect, compared to totally untreated patients, is difficult...", and, again, not likely to yield similar results across dissimilar studies. 198.49.180.40 22:05, 5 April 2007 (UTC)

[edit] What if there is no Subject?

I'd like clarification on the definition of a double blind study. What if there is an ignorant experimenter, but no subject at all? For instance, suppose we give three weapons to a ballistics expert and ask him which one fired a given bullet? Would that be a double blind test, even though there is only one person (the experimenter) unaware of the correct answer? —The preceding unsigned comment was added by 68.6.94.12 (talk) 16:33, 31 March 2007 (UTC).

Well, that isn't an example of a "study" at all. You're talking about an applied materials test with one sample, not a research experiment with a pool of subjects. Also, evaluating a therapeutic outcome is a really different problem than what you have described. Every patient won't have an identical outcome even after a well-tested therapy is provided, blindly or otherwise. Your example is basically the same though as what's described under "Forensic application". The only difference is that you're trying to have someone identify a bullet rather than a person. That person may or may not be biased, and the same is true of the person who's providing the samples to the tester. 198.49.180.40 21:14, 5 April 2007 (UTC)
Thank you for the reply. However, I'm still unclear on one thing: Is an experiment "double blind" whenever observer bias is mitigated by denying the observer knowledge of the expected outcome? Or does "double blind" have a narrower definition, and only applies to therapeutic studies with a pool of subjects who are also blinded? In effect, I'm asking whether the term means what it literally means, or whether its meaning has drifted -- preserving the valuable concept at its core, but dropping less significant details -- to the point where it applies to more situations than originally intended, including the ballistics example I cited above.
I ask because I've heard "double blind" applied to questionable situations, and I'm not sure if that is because of ignorance, or because the term is widely understood to have a meaning more flexible than the one described here in Wikipedia. Language is a slippery thing, and words tend to mean what people think they mean. I suppose I'm asking what people really think "double blind" means.
By the way, I can see how my ballistics example is similar to the photo lineup cited in the article, but that doesn't help answer my question. In the lineup example, the officer is conducting a single blind test of the witness' memory, but isn't the witness also conducting a test? And since the observer in the witness' test is different from the observer in the officer's test, might it be possible that the witness' test is double blind even though the officer's is not? Returning to my ballistics example, it seems reasonable to ask whether the ballistics expert is conducting a double blind test, regardless of what is known by the person providing the samples. —The preceding unsigned comment was added by 68.6.94.12 (talk) 18:22, 10 April 2007 (UTC).
In "single blind", the subjects are blinded but not the doctors. In "double blind", both the doctors and the subjects are blinded.
In your ballistics example, what would be the "single-blind" analogue? Presumably, the bullets themselves are not ignorant (blind). The same would be true in the photo lineup: the witness and the photo subjects are not blind, though the detective might be, or or might not. So, how are you imagining a case that would NOT be described as double-blind, in contrast to what you already described?
Lastly: I fully expect researchers to use research terms (like "double-blind", for example) differently from how the general public does. The meaning-drift you mention occurs thus, though I'd argue that intended meaning on the part of an ignorant utterer does not convey any actual meaning in the utterance. 198.49.180.40 22:13, 10 April 2007 (UTC)
I'm mostly interested in the meaning-drift issue, and you've addressed that. If I understand correctly, you are insisting that "double blind" applies only when there are experimenters and subjects, and both are blinded. I'm satisfied with that answer.
On the principle that no question should be left hanging, I'll answer the questions you asked in your last reply: When I've heard "double blind" used in situations similar to the ballistics example, there is no analog to "single blind"; there is only "double blind" and "unblinded". An unblinded test would be one in which the experimenter is aware of the expected outcome (e.g. "Here is the suspect's gun. Tell us if it fired the bullet."). I have no doubt that there is a valid distinction to be made between a blinded and unblinded experimenter in cases like these. What is at question is whether the term "double blind" can be used to make that distinction. You've given me the answer no.
By the way, I'm surprised at your claim that intended meaning conveys no actual meaning. I'd love to debate that with you, but perhaps we should do that in a linguistics forum somewhere, rather than this page. In any case, thanks for the time you spent responding to my questions here. —The preceding unsigned comment was added by 68.6.94.12 (talk) 03:13, 11 April 2007 (UTC).

[edit] Single blind

Is anyone against merging it here? For that matter, why not just have an article on blinding in general that covers all forms? Richard001 05:31, 24 April 2007 (UTC)

A very good idea. It was the first thing I thought when I googled for information on blind experiments and found two wikipedia articles covering the same thing. As such I have done a rather crude merge and am more than happy for others to continue the process. I agree that the article could be renamed to a more general blinding title.
On a completely unrelated idea, I would like to see further discussion of the ethical implications of double-blinds. I have been led to believe that here in Australia there are a number of situations where it is deemed unethical to conduct a double-blind and I would like to know more about this and see it included in the article. Fermion 10:38, 25 July 2007 (UTC)

[edit] What's it called...

when an experimenter tells the subject that something is X but then switches X with Y in order to observe the existence of the subject's bias? does it have a name? --AnY FOUR! 04:46, 4 August 2007 (UTC)

[edit] ABX testing

I'm an ex-subjective audio reviewer (Stereophile) who's had terrible arguments with Arny Krueger, et al, about problems with controlled testing -- namely, that listening under controlled conditions is not the same as listening casually (which is how we actually listen to music). This point -- that controlling the test conditions can also alter them -- needs discussion. WilliamSommerwerck (talk) 14:57, 15 February 2008 (UTC)

[edit] Not ubiquitous

Blinding is far from ubiquitous in the scientific method. It is relatively rare in chemistry, physics, geology, meteorology, astronomy, and forensic science. It is even relatively rare in many areas of biology and medicine. I recently reviewed a number of grant proposals related to traumatic brain injury; less than 10% included blinding in their proposed methods. Michael Courtney (talk) 11:45, 1 April 2008 (UTC)