Users' Guides to the Medical Literature
Guyatt G, Rennie D, Meade MO, Cook DJ
Part A The Foundations
Chapter 5. Why Study Results Mislead: Bias and Random Error
Gordon Guyatt, Roman Jaeschke, Maureen O. Meade
Why Study Results Mislead: Bias and Random Error: Introduction
Topics Discussed:
bias (conflict of interest), bias, epidemiologic, conduct considerations, misleading results, random error
Excerpt:
"Our clinical questions have a correct answer that corresponds
to an underlying reality or truth. For instance, there is a true
underlying magnitude of the impact of 
-blockers
on mortality in patients with heart failure, of the impact of inhaled
steroids on exacerbations in patients with asthma, and of the impact
of carotid endarterectomy on incidence of strokes in patients
with transient ischemic attacks. Research studies attempt to estimate
that underlying truth. Unfortunately, however, we will never know
what that true impact really is (Table 5-1).
Studies may be flawed in their design or conduct and introduce systematic
error (bias). Even if a study could be perfectly designed
and executed, we would remain uncertain whether we had arrived at
the underlying truth. The next section explains why...."
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