There were serious flaws with reports that a study found neck fleeces are worse than not wearing a mask at all

Paco Freire/SOPA Images/LightRocket via Getty ImagesBARCELONA, CATALONIA, SPAIN – 2020/07/21: A mannequin with the equipment of the Barcelona Football Club in the Maldá Galleries during the coronavirus pandemic.
  • In a widely reported study, researchers at Duke University studied how to test the efficacy of face masks.
  • Reports suggested the study compared the effectiveness of the masks, concluding a neck fleece is worse than no mask at all.
  • But the study only tested a neck gaiter on a single person, a sample size too small to determine its effectiveness, which wasn’t the goal of the study.
  • This story has been updated to reflect that the study was designed to test ways of measuring a mask’s effectiveness, not which masks are most effective.
  • Visit Business Insider’s homepage for more stories.

A study from Duke University researchers swept the internet this month, reportedly finding that people who wear neck gaiters would be safer wearing no mask at all.

But that wasn’t the case. Those conclusions misstate the goal and scope of the research, and are based on a limited test of a single person wearing a gaiter.

The study involved a control group of people not wearing any masks, and test group of people speaking 10 times while wearing different types of masks, such as surgical masks, N95 masks, cotton masks, and polypropylene masks, as well as homemade alternatives such as neck fleeces and bandanas.

The researchers found that most of the masks reduced the number of respiratory droplets transmitted compared with the control group, adding to the body of evidence that masks are important in helping to limit the spread of the coronavirus. They found that polypropylene masks transmitted a similar number of droplets as surgical and N95 masks, which transmitted the fewest droplets.

The neck fleece and bandanas, however, had higher counts of respiratory droplets. In fact, the researchers found that the neck fleece increased the number of respiratory droplets by creating several smaller droplets from larger ones, resulting in more droplets than not wearing masks at all.

It’s true that some masks may be more effective than others. The World Health Organisation’s guidelines recommend homemade face masks have three layers, and that people wash them regularly and wear them correctly.

14 types of masksEmma Fischer, Duke UniversityResearchers used 14 kinds of mask to test whether their method could help determine masks’ effectiveness.

But across most of the coverage of the study, including in a previous version of this article by Business Insider, these results were framed out of context. The study was not looking at the effectiveness of masks. In fact, researchers were studying how to measure a mask’s effectiveness.

This is a key distinction since, as the researchers themselves note, the results were not intended to be comprehensive, but just to demonstrate that the methodology could work for larger-scale studies on masks to help compare their effectiveness.

“We do not attempt a comprehensive survey of all possible mask designs or a systematic study of all use cases. We merely demonstrated our method on a variety of commonly available masks and mask alternatives with one speaker,” the study reads.

There’s a reason scientific studies don’t rely on a sample size of one to draw conclusions – with a single person, there could be variables that the researchers didn’t foresee that affect the results. That’s why scientific research requires results to be verified many times, with close attention to possible confounding variables, before drawing conclusions.

As a result, it’s not yet entirely clear how neck gaiters measure up in terms of effectiveness, and more research is needed.

Editor’s note: This story has been updated to reflect that the study was designed to test ways of measuring a mask’s effectiveness, not which masks are most effective.

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