Scientific Method - How Double Blind Clinical Trials Are Done

[plan101]

including this in my Theo van Gogh major paper for University Of Toronto . To determine the actual result of the film.

[dineshseosharp]

I like this. you provide a good information. it is very useful to me. Clinical Research Services across the Globe by Informatics Outsourcing (Case Report Form Design)

[DoctorFist]

So..its not possible to do a double-blind study on placebos? I heard that in some cases they were as effective as the drugs they were meant to replace. I wonder if science will ever get into finding an unbiased way to measure the influence of bias or personal belief, if thats possible

[theinquisitor]

From what I've heard, the placebo effect can be studied with scientific methods. It's essentially a psychological phenomenon, and trials which compare some types of placebos with others can get some interesting results. Such as, two pills have a greater placebo effect than one, and an expensive placebo has more effect than a cheap one.

The speaker in this video makes a podcast called Skeptoid, and talks about this issue in one of the short episodes. To find it, google: skeptoid placebo.

[marksbooker]

There's even more fascinating effects from the placebo phenomenon. Such as you can stop pain relief from the placebo effect by injecting an opiate blocker. Which means that the placebo has an actual physical effect on the brain which can be manipulated.

Also in recent decades the placebo effect is getting stronger, but only in some regions. There are places in the world where the placebo effect is statistically weaker than in other regions. And no one really knows why.

[theinquisitor]

Interesting. I hadn't heard about those aspects of the placebo effect. I'm curious about where you came across this information.

Although it's worth noting that (as far as I know), the placebo effect is only effective at altering subjective symptoms, like pain. It can't cure disease or mend damaged tissue.

Fortunately, real medicine also generates the placebo effect and so you can get the best of both worlds, whereas so-called "alternative" medicine almost always provides just the placebo.

[marksbooker]

For the placebo opioid blocking thing check the wikipedia article for placebo under 'Mechanism of the effect'. They talk about the experiment there.

And the placebo effect getting stronger comes from a Wired article titled 'Placebos are Getting More Effective'. It's a very interesting read.

[theinquisitor]

Cool, thanks. I'll check those out.

[roshoLinux]

Check it for good, because it's talking about depression, not AIDS.

[DonHoraldo]

if only that where so. but every day the people create studies completely unblinded and then say any effect is a positive result. then the public get's a hold of it and crap resists.

[just0ten]

surely this is common sense, however if it is not may this video make it so.

[theinquisitor]

Indeed, but almost every time I see a demonstration of an experiment on television, they do it with one subject and create the impression that this is how real science is done. They don't even mention the fact that they do multiple experiments and I've never once heard the phrase "double-blind placebo controlled trial" mentioned on television... ever. Hopefully this kind of new media will eventually correct those mistakes. Don't forget to check out the whole documentary, links in description box

[SexyMelon]

This deserves way more views.

[nhojmabon]

agreed.

[kjlg74]

This deserves way more than 389 views. The concepts taught in this clip are vital pieces of knowledge for making reasoned critical judgments about many types of medical claims.

[psandbergnz]

This is a good reason why the random controlled trials performed in 2005/6 in Africa to establish the effect of male circumcision on HIV transmission are so unreliable. Obviously, these HIV trials could not be done double- or even single-blind, since the participants (subjects) and investigators were fully aware whether the participants were placed in the circumcised or the control group.

[Ashermans]

They could be double blinded as it's possible that the doctors/researchers were unaware of the circumcision status of the subjects which would only be known if they were naked, something that is not needed to take bloods for an ELISA test. Also, the statisticians could be blinded too. It would be impossible to blind the subjects to their own foreskin status but thisis irrelevant to the results-infection is not influenced by subjects' awareness , like say side effects from drugs would be.

[psandbergnz]

Asherman, you don´t understand what "double-blinded" means. Double-blind means that all investigators involved AND patient don´t know in which group (Control or Circumcised) the patient belongs. At best, the trials could be SINGLE-BLIND (they weren´t).

Your claim that it is irrelevant whether the patients knew or didn´t is ignornant too. What makes you so certain that this awareness would not affect sexual behaviour?

Note the circumcised group had to be given SPECIFIC instructions.

[Ashermans]

psanbergnz, I stand by my original statements-your response shows misunderstanding about RCTs. Plus, I did say that knowledge can possibly affect behaviour -please reread my original response. I don't have an opinion one way or the other but it seems like you have a bias which you try to support 'scientifically'. This is poor science.

[Ashermans]

psandbergnz, since I obviously need to spell it out to you, double blinding means that two of the groups are blinded- this can be patients and test administrators (ie researchers), but it can also be researchers and statisticians. See 1:13 when he talks about triple blinding ie patients, researchers and statisticians. Furthermore, no one is given 'specific' instructions on how to behave- where did you get that from? Look up the original research article(s) if you actually have access to them.

[psandbergnz]

Ashermans, you reveal your own ignorance and untruthfulness. Doouble-blind ALWAYS implies that the subject is unaware of his condition (in addition to researchers). If the patient is not "blinded", then the trial is not double-blind! Futhermore, you are wrong about "specific instructions". The circ'ed men had SPECIFIC INSTRUCTIONS to abstain from sex during wound healing (usually 4-6 weeks).

You did not say/imply that knowedge can affect behaviour! If you did, please QUOTE (lol!)!

[IceAges14Aces]

@psandbergnz The problem with double-blindness is that even though the experiments look and sound double-blind, it may actually not be double-blind. There are many mundane factors in the basis of double-blind experiments that contanimate the data. These factors are: 1) Experimenters tell test-subjects that these pill may or may not be real, 2) placebo pills look fake to test-subjects, 3) even a tiny hope/negative from test-subjects can contanimate the data........

[Ashermans]

Also, if anything, subjects who were circumsized to test if it protected against HIV might be even more inclined to participate in risky behaviour, biasing results to increase infections in this group-and despite this, they had lower infection rates than the control group. Getting the hang of scientific thinking?

[Funkypotat0]

I finally understand what double blind is now. Thanks for sharing this.

[TrueNorth15]

this was a great documentary