At 12:23 AM 9/27/96 -0400, Joao Paulo wrote:
>
>Which is the meaning of this expression "double-blind" exactly ?
People's reactions to substances ingested can be guaged more
accurately if some of them get the medicine or whatever and some of them get
placebos or sugar pills that look just like the medicine. If those
getting the real thing are helped and those getting the placebo are not
helped, then it is safe to assume that it was the efficacy of the medicine
that brought about the help rather than positive thinking or faith healing
or some other mental/spiritual process engaged in by the reipient who
believed help was coming.
Sometimes those dispensing the medicine give away clues, in what
they say or how they behave, to permit reipients to determine if they are
getting the real thing or just the fake thing. This could skew results.
Moreover, sometimes those dispensing the medicine expect different results
in those getting the real thing and that expectation may cause them to
"observe" different results which really don't exist except in the
dispenser's mind. To counteract this, studies can be double-blind by not
letting the dispensers or the recipients know which pills are real and which
are fake.
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