Tag Archives: causation

Bias or comorbidity? Risk factors for respiratory disease aren’t always what they seem

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About Tara Haelle

Tara Haelle (@TaraHaelle) is AHCJ's medical studies core topic leader, guiding journalists through the jargon-filled shorthand of science and research and enabling them to translate the evidence into accurate information.

Bias or comorbidityBy this point, anyone who’s been covering or following COVID-19 knows that several comorbidities substantially increase the risk of complications and severe disease. Among those mentioned most often are diabetes, heart disease and obesity.

We learned of the associations between those conditions and more severe disease first from clinical anecdotes, then case series, then observational studies. But observational studies can almost never show causation. (I don’t think they can ever, on their own, show causation, but I add the “almost” because nothing in science is ever absolute.) Although diabetes is linked to poorer outcomes with COVID-19, it doesn’t mean having diabetes causes poorer outcomes. Continue reading →

Caveats about causality in medical studies linked to more accurate news coverage

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About Tara Haelle

Tara Haelle (@TaraHaelle) is AHCJ's medical studies core topic leader, guiding journalists through the jargon-filled shorthand of science and research and enabling them to translate the evidence into accurate information.

Photo: Jacob via Flickr

It’s a well-worn mantra: Correlation does not equal causation. But even if we know this, is it always accurately and responsibly reflected in our stories and headlines?

It can be simpler and more elegant to say “Vodka causes sexually transmitted infections” in a headline than “Vodka consumption associated with increased risk of sexually transmitted infections.” (Note: This is not a real headline or based on a real study.) But in this made-up example, it’s laughably obvious that vodka itself does not cause STDs. Continue reading →

Panelists explain how to begin mastering medical studies

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About Joseph Burns

Joseph Burns (@jburns18), a Massachusetts-based independent journalist, is AHCJ’s topic leader on health reform. He welcomes questions and suggestions and tip sheets at joseph@healthjournalism.org.

Comic by xkcd.com

At some point almost all health care journalists will need to cover a medical study or two. When that happens, you’ll want to have at least a passing understanding of p values and statistics and you’ll need to know that correlation does not imply causation.

For a session on May 2, AHCJ’s medical studies topic leader Tara Haelle moderated a panel, “Begin mastering medical studies.” Haelle and two experts in the topic explained some of the finer points of covering studies: Ishani Ganguli, M.D., an assistant professor of medicine at the Harvard Medical School, and an internal medicine physician at Brigham and Women’s Hospital; and Regina Nuzzo, Ph.D., a freelance journalist and professor of science, technology and mathematics at Gallaudet University. Continue reading →

Caution required when discussing associations between oral and overall health

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About Mary Otto

Mary Otto, a Washington, D.C.-based freelancer, is AHCJ's topic leader on oral health and the author of "Teeth: The Story of Beauty, Inequality, and the Struggle for Oral Health in America." She can be reached at mary@healthjournalism.org.

The mouth is connected to the body.

Yet much remains unknown about the subtle workings of that connection.

Research continues to identify associations between oral and systemic conditions. But it is too soon to draw conclusions about possible causal relationships between maladies such as gum disease and cancer, warn the authors of a June guest editorial in the Journal of the American Dental Association. Continue reading →

Sex & money: When correlation isn’t causation, studies can still inform

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About Brenda Goodman

Brenda Goodman (@GoodmanBrenda), an Atlanta-based freelancer, is AHCJ’s topic leader on medical studies, curating related material at healthjournalism.org. She welcomes questions and suggestions on medical study resources and tip sheets at brenda@healthjournalism.org.

Image by Susan Sermoneta via flickr.

Two recent studies in the news have been clear examples of the correlation vs. causation question that’s part and parcel of covering observational research studies.

And they’re worth taking a look at because the correlations are inherently interesting, even though they almost certainly aren’t causal.

First up is “The Effect of Sexual Activity on Wages”, which was published by Germany’s Institute for the Study of Labor.  Predictably, and probably in part due to its terrible title, this study generated lots of headlines like “Have more sex, make more money”, from The Wall Street Journal‘s Marketplace, and Cosmopolitan‘s “The More Sex You Have The More Money You Make“.

Well, not exactly. The study found an association between sex and wages. As self-reported sex increased, so too, did income. Of course, that doesn’t mean that having more sex causes people to make more money, a point that wasn’t stressed clearly enough in some articles for Scientific American blogger Evelyn Lamb’s tastes. Continue reading →