Scientific Method - How Double Blind Clinical Trials Are Done

Clip from the 40 minute video introduction to critical thinking called "Here Be Dragons", written and presented by Brian Dunning.

http://herebedragonsmovie.com

Link to full documentary:
http://www.youtube.com/watch?v=OKdG7yGi0KA

This clip explains the vigourous process of double blind clinical trials, and shows how they are designed to avoid being influenced by accidental or intentional biases.

Here Be Dragons is written and presented by Brian Dunning, host and producer of the Skeptoid podcast and author of Skeptoid: Critical Analysis of Pop Phenomena, and Executive Producer of The Skeptologists.

Category:

Education

Tags:

• medical
• clinical
• trials
• double
• blind
• test
• science
• critical
• thinking
• scientific
• method

[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.

[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.

[TrueNorth15]

this was a great documentary

[plan101]

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

[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........

[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)

[roshoLinux]

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

[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!)!

[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.