Because the lives and wellbeing of patients will be influenced for better or worse by the
validity of these judgments, however, it is important to be explicit about the logic as well as …

Randomised controlled trials and observational studies are often seen as mutually
exclusive, if not opposing, methods of clinical research. Two recent reports, however …

The view is widely held that experimental methods (randomised controlled trials) are the
“gold standard” for evaluation and that observational methods (cohort and case control …

Evaluations of healthcare interventions can either randomise subjects to comparison
groups, or not. In both designs there are potential threats to validity, which can be external …

High quality randomised trials provide unbiased estimates of the effects of health
interventions, but the findings of a single trial are rarely conclusive. Usually data from …

The rise of evidence based health care has high-lighted the use of ineffective interventions,
the risks of uncoordinated research, and the consequences of relying on studies published …

This article is part of a series featured from the Catalogue of Bias introduced in this volume
of BMJ Evidence-Based Medicine that describes biases and outlines their potential impact in …

There is increasing pressure on healthcare professionals to ensure that their practice is
based on evidence from good quality research, such as randomised controlled trials or …

Uncertainties about the effects of treatments are inevitable. Whatever the basis for
judgments about the likely effects of treatments in individual patients, there is no escape …

What do patients want from doctors in the way of treatment? Only what is best for them as
individuals. Doctors want and intend the same for their patients. Sometimes there is …