Letter

Confounding and Simpson's paradox

BMJ 1995; 310 doi: 10.1136/bmj.310.6975.329b (Published 4 February 1995)
Cite this as: BMJ 1995;310:329.3

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Multiple regression would confound the clinicians

  1. C R Charig
  1. Consultant urologist Epsom General Hospital, Epsom, Surrey KT18 7SG

    EDITOR,—Steven A Julious and Mark A Mullee discuss confounding and Simpson's paradox, defining confounding as occurring “when the association between an exposure and an outcome is investigated but the exposure and outcome are strongly associated with a third variable. An extreme example of this is Simpson's paradox, in which this third factor reverses the effect first observed.”1 In their analysis of my and colleagues' …

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