Hi Ben.
I would think that the operative question might come in two strengths:
Weak: "What study designs can provide strong-enough evidence that a relationship is causal that to act on that evidence (particularly when physiologically and otherwise plausible) would be widely be considered to be responsible?" (E.g., statins for secondary prevention of CAD)
Strong: "What study designs can provide strong-enough evidence that a relationship is causal that not to act on that evidence would be widely be considered to be irresponsible?" (E.g., aspirin in acute MI)
This approach grants that Hume set a standard that renders the proof of causality impossible (by definition)--and regards that standard as irrelevant to life in the world, where the issue is to balance the resources for creating evidence against the estimated impacts of Type I and Type II errors, and so forth. (See Nobel laureate Herbert Simon's concept of satisficing, reference below.) For example, if the patient is poised to die, much weaker evidence is needed to justify an intervention than in the case of proposed disease prevention in asymptomatic individuals.
Simon, H. (1971). Designing Organizations for an Information-Rich World. Computers, Communications, and the public Interest. M. Greenberger. Baltimore: 44.
Best regards.
Jim
James M. Walker, MD, FACP
Chief Health Information Officer
Geisinger Health System
>>> "Djulbegovic, Benjamin" <[log in to unmask]> 1/28/2011 10:06 AM >>>
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
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