A caveat about active voice and conciseness

correlation vs causation

Thanks to Tracy Allison Altman over at Evidence Soup, I just read Does the Language Fit the Evidence by Mark Zweig, MD, and Emily DeVoto, PhD. The authors are concerned about the translation of medical research into popular media stories. Here’s why:

A subtle trap occurs in the transition from the cautious, nondirectional, noncausal, passive language that scientists use in reporting the results of observational studies to the active language favored in mass media. Active language is fine in general – who wants to write like a scientist? But problems can arise when the use of causal language is not justified by the study design.  For example, a description of an association (e.g., associated with reduced risk) can become, via a change to the active voice (reduces risk), an unwarranted description of cause and effect. There is a world of difference in meaning between saying “A was associated with increased B” and saying “A increased B.” The difference may seem subtle in terms of language, but is large in terms of meaning.

Check out Zweig and DeVoto’s table comparing researchers’ versus journalists’ wording of results from observational studies, which can signal only associations (or correlations) rather than cause-effect. Here’s one pair of them.

  1. Long-term daily use of adult-strength aspirin may be associated with modestly reduced overall cancer incidence conveys an association between aspirin and cancer in 15 words and passive voice.
  2. Higher aspirin dose seems to stave off some cancers conveys causation between aspirin use as the incidence of cancer in  9 words and active voice.

As the authors note, only a randomized trial could rule out the possibility of other causes for reduced incidence of cancer. So sentence (2) is not accurate based on the research.

A good reminder that The Truth sometimes requires more rather than fewer words.

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One Comment

  1. I don’t think this (the example given in this post) is even just a case of changing the passive to active. The original “may be associated with” is extremely cautious—even the alleged association is only tentative.

    And, of course, as the New Yorker article I mentioned earlier shows, even randomized trials don’t really prove causation. They just seem to do so, at least for the first couple of years.

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