1. I think that, distinguishing between the cause and effect vs. coincidences, as coincidences means hazard, is the role of statistics (type I,
alpha, error).
2. RCT are superior to observational studies
in establishing cauzality not by distinguishing it from coincidence, but by
eliminating confounding: selection bias by randomisation, and some
other less important bias (performance and detection=ascertainement bias by
blinding, attrition bias by ITT analysis).
For causality issues, one might use the Bradford
Hill criteria, which are said to be "neither sufficient, nor necessary" (this
means...useless??). They may vary from textbook to textbook, but study
design is important because of temporal relationship, too (cause must
precede effect, RCTs and cohort studies are supperior to the
others).
----- Original Message -----
Sent: Friday, January 28, 2011 5:06
PM
Subject: Can RCT help establish
causation?
Dear all
I'd like to post this question to the group that I have been thinking
about for some time... Is there a scientific method that allows us to
LOGICALLY distinguish the cause-effect from the coincidence? David Hume,
one of the most influential philosophers of all times, concluded that there is
no such a method. This was before RCTs were "invented". Many people have
made cogent arguments that (a well done) RCT is the ONLY method that can allow
us to draw the inferences about causation. Because this is not possible in the
observational studies, RCTs are considered (all other things being equal) to
provide more credible evidence than non-RCTs. However, some philosophers have
challenged this supposedly unique feature of RCT- they claim that RCTs
cannot (on theoretical and logical ground) establish the relationship
between the cause and effect any better than non-RCTs. I would appreciate some
thoughts from the group:
1. Can RCT distinguish between the cause and effect vs. coincidences?
(under which -theoretical- conditions?)
If the answer is "no", is there any other method that can help establish
the cause and effect relationship?
I believe the answer to this question is of profound relevance to
EBM.
Thanks
Ben Djulbegovic