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Statistics for Business and Economics: Excel/Minitab Enhanced
Heinz Kohler
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Statistics in the News: Chapter 5 Generating New Data: Controlled Experiments

Mind Over Matter

According to popular opinion, the mind can influence the course of a disease so powerfully that patients can hold off death by getting emotional support in a group. Some researchers recently tested the story by designing an experiment involving 235 women with advanced (metastatic) breast cancer. All of the subjects were expected to live at least 3 months and received routine medical care. However, a random selection also assigned 158 women to group therapy, while such additional help was withheld from 77 others. Crucial results are summarized in Table A.

TABLE A Results of Breast Cancer Study










Median Survival


Relative Risk Ratio for Death

95% Confidence

Interval for Relative Risk Ratio


(received therapy)


17.9 months


.78 - 1.45


(no therapy)


17.6 months



The researchers concluded that psychological intervention did not prolong survival. The idea that one might cure cancer in the body by vanquishing it in the mind was nothing but wishful thinking.

Note: There was, however, a transient effect. Group therapy did improve the mood and perception of pain among those who were exceptionally distressed initially. Thus, therapy improved the quality of life for some, although not its quantity. Some women lived better, although not longer. In that sense, mind mattered.



Sources: Adapted from Pamela J. Goodwin et al., "The Effect of Group Psychological Support on Survival in Metastatic Breast Cancer," The New England Journal of Medicine, December 13, 2001, pp. 1719-1726; David Spiegel, "Mind Matters—Group Therapy and Survival in Breast Cancer," ibid., pp. 1767-1768; and Gina Kolata, "Study Rebuts Belief That Support Groups Can Extend Life," The New York Times, December 13, 2001, p. A22.

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