JOSEPH D. SAPIRA, M.D.
To the editor: The two articles on biofeedback in the August issue (1, 2) both damn with faintest praise the study of fecal incontinence by Engel and coworkers (3), complaining of the absence of a control group among other things. On the surface it does not seem fair to criticize on these grounds when at the same time Dr. Marzuk states it is "difficult to define what experimental conditions constitute an adequate control group for biofeedback."
In fact, it is easy: A "yoked" control would be a matched subject (patient) randomly assigned to the control group. This patient's sessions would
SAPIRA JD. Study Design: Two Standards?. Ann Intern Med. 1985;103:810. doi: 10.7326/0003-4819-103-5-810_1
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Published: Ann Intern Med. 1985;103(5):810.
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