Perils of Clinical Trials

One day when I was a junior medical student, a very important Boston surgeon visited the school and delivered a great treatise on a large number of patients who had undergone successful operations for vascular reconstruction.

At the end of the lecture, a young student at the back of the room timidly asked, “Do you have any controls?” Well, the great surgeon drew himself up to his full height, hit the desk, and said, “Do you mean did I not operate on half the patients?” The hall grew very quiet then. The voice at the back of the room very hesitantly replied, “Yes, that’s what I had in mind.” Then the visitor’s fist really came down as he thundered, “Of course not. That would have doomed half of them to their death.”

God, it was quiet then, and one could scarcely hear the small voice ask, “Which half?”

— Dr. E. E. Peacock, Jr., quoted in Medical World News (September 1, 1972), p. 45, as quoted in Tufte’s 1974 book Data Analysis for Politics and Policy.

Hat tip to Alex Tabarrok.

Comments (6)

Trackback URL | Comments RSS Feed

  1. Paul H. says:


  2. Larry C. says:

    Funny? Yes. Clever? Yes. But what is the right answer?

  3. Devon Herrick says:

    There’s an old saying that goes something like this: half of the procedures doctors perform are either unproven, ineffective or potentially harmful. The problem is: we don’t know which half.

  4. Nancy says:

    This whole discussion is making me lose faith in the medical profession.

  5. Linda Gorman says:

    Sometimes a randomized trial is a waste. For example, if every person who gets X dies, and then people with X are given a drug and most of them live, there is clear evidence of benefit.

  6. Virginia says:

    Great story.