[LINK] Re: Double Blind Trials (Was to do with EMF)
rchirgwin at ozemail.com.au
rchirgwin at ozemail.com.au
Fri Jan 12 18:32:06 AEDT 2007
Kim Holburn wrote:
>
> On 2007/Jan/12, at 12:25 AM, Stewart Fist wrote:
>
>> The reason why double blind trial are used, is not because of the
>> placebo
>> effect, but because it is vitally important to rule out overt and
>> covert
>> influence in recording the results by the investigator.
>>
>> It is a problem of the 'witness' not the patient. It is well known
>> that
>> investigators who believe in the efficacy of a new drug will either
>> consciously/deliberately or unconsciously err on the side of recording
>> positive results.
>>
>> Blind trials exist to stop this trend.
>
>
> I hadn't thought about it quite like that. Do you think then, that
> the placebo effect is just a virtual effect for the purposes of drug
> testing and not something that's really happening at all?
It's more complex than that. "Placebo effect" is, anyway, a pop-culture
shorthand for a complex phenomenon. Summarising this:
http://en.wikipedia.org/wiki/Placebo
(sorry to those who object to WP)
1) Drug and placebo are equally ineffective
2) Drug is effective but has nasty side effects.
3) Drug is ineffective *and* has nasty side effects
And:
1) Side effects are noticable before the drug's desired effect
2) Side effects are slower
So. What's perceived as a placebo effect may be:
- the placebo doesn't cause side-effects, so people using the placebo
report feeling better than those using the active drug
- the subjects recognise that they're receiving a placebo (because of
the lack of side effects), which effects how they report how they're feeling
- the subjects genuinely can't tell, in which case the outputs of the
study can be trusted
...and so on.
Even in the double-blind test, the presence or absence of side-effects
is a big marker to the recipient.
Because this all gets shorthanded, people believe that there's a simple
something called the 'placebo effect' which everybody knows about and
has been proved and measured and so on. It's no such thing; it's a
debateable artefact of measurement which may reflect patient psychology,
or may reflect the way drug tests are conducted, or ...
RC
>
> Kim
>
> --
> Kim Holburn
> IT Network & Security Consultant
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> -- Lloyd Biggle, Jr. Analog, Apr 1961
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