BMJ 1994;309:540 (20 August)

Letters

Experimental and observational methods of evaluation

EDITOR, - Trevor A Sheldon's editorial perpetuates the false dichotomy between experimental and observational research.1 Once again an advocate of randomised controlled trials seeks to discredit evaluative research that uses observational data as if the two methods were alternatives rather than complementary approaches. Extremist supporters of either camp offer unacceptably simple accounts.

Of course in some people's ideal world every intervention in the biological and social spheres would be evaluated with a randomised controlled trial. But the world is not such a utopia. As a consequence there are important roles for observational methods used with the care and rigour that, hopefully, trialists bring to their studies. What are those roles?

Firstly, some interventions, such as defibrillation for ventricular fibrillation, have an impact so large that observational data are sufficient to show it.

Secondly, infrequent adverse outcomes would be detected only by randomised controlled trials so large that they are rarely . . . [Full text of this article]


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Relevant Article

Please bypass the PORT
T A Sheldon
BMJ 1994 309: 142-143. [Extract] [Full Text]

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