“Less work in the household can lead to weight problems for women. With this news I have been opening my critical thinking course for eight years now. The study on the use of time at home was then very publicized. Even Medscape, a trusted source for medical news and information for physicians, headlined “Historic Decline in Housework Contributes to Female Obesity.”
The interest in this study was the reason why the course was set up. I was appalled that so many major news organizations wrote about the investigation in such an uncritical manner. Their stories seem so plausible: Since 1965, when the study began, women have spent less time doing household chores, which has contributed to the increase in obesity. Presumably, perhaps, but that conclusion did not flow from the investigation, and no journalist pierced it.
It always amazes me how easily people, including journalists, assume that science will make sense. Why is it like this? Is it the fear of science? Should we expect science to be probably too complicated for a layman to understand? There is a lot of complicated science out there, but studies like the Household Study are not one of them, they are better understood. And that’s what the course teaches.
Last week, I presented the news to a new group of around 30 undergraduate students with the question: what type of study is behind the news? Students are first to fourth year students in a variety of fields of study, from health sciences to Jewish studies and dance. Only two students took a course in epidemiology.
At the start of the course, most students do not know what to do with this question. They have no idea how scientific research is done. This is why I am going to give you an overview of what you might be wondering. Who are the participants? How long does the investigation take? What data is collected? But also: how do researchers know that it is precisely the reduction in household chores that leads to obesity?
We describe the research based on these questions. A long-term cohort study in which a group of women are asked every few years to keep track of how they spend their time and weigh themselves for a week is consistent with the finding that less time spent in the gym. outbreak can lead to weight problems. . With this data, you can determine if a change in time use is related to a change in weight. Whether you can then conclude that less household chores ‘can lead’ to obesity depends on whether you have been able to rule out alternative explanations: those who spend less time in the kitchen may eat ready-made meals more often – how often? is the culprit?
But the study was not a cohort study. The data comes from a US diary study in which a new group of women kept a diary of their time every five years from 1965 to 2010. These diaries showed that during this 45-year period, women spent less and less time on household chores and more and more time sitting in front of the television or computer. That was it. No scale was used throughout the study.
The link between housekeeping and obesity had not been studied. It was a speculation, a suggestion. Because obesity had increased during this same period. The fact that women began to work outside the home en masse during the same period and were burning their energy elsewhere was not taken into account. The role of diet has also not been studied. And that of soft drinks either. The research was funded by Coca Cola.
This example is extreme, but is no exception. In the coming weeks, we’ll be discussing the science behind the current news in the course, and I also don’t expect a shortage of examples this time around. Why not? Because news articles often rely heavily on press releases from universities and research institutes, and these primarily highlight what makes research so special and newsworthy. There is no room for critical comments.
And this is where it goes wrong. These caveats are essential. The conclusion stands or falls with the way the research was put together. I don’t find it surprising that vitamin D supplements don’t help with depression when I read that 90 percent of the participants were not vitamin D deficient.
And that the number push ups I find it very unlikely that someone could do this successively to predict the risk of cardiovascular disease when I read that the participants, fit firefighters, had to do push-ups eighty times per minute and they were already losing weight if they miss three metronome beats. Such details put the conclusions in a different light.
My students will not be able to read a news article without asking questions at the end of the course. They know then that a lot of news is not what it seems and that they are able to find out what is behind it. I feel privileged to be able to teach them this.
Cecile Janssens is Professor of Translational Epidemiology at Emory University in Atlanta.
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