The Latest Casualties of the False Cause Fallacy

Correlation does not mean causation.

It’s a science message that bears constant repeating. When a headline or politician conveys a cause-effect conclusion based on correlational evidence, that’s the false cause fallacy, and it continues to be a problem in public understanding of research about groups of people.

I’ve previously discussed such coverage or judgments about immigrants, young social-media users, police officers, and many others (Stalder, 2025). And I’ve since noticed many new examples. They include night owls, remote workers, and time buyers.

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Night Owls

Based on over 300,000 adults in the UK, a recent study reported that night owls showed poorer overall cardiovascular health (Kianersi et al., 2026). Although the research was correlational, headlines included that “Being a Night Owl Is Bad for Your Heart” (Carefoot, 2026) and “What Staying Up Late and Being a ‘Night Owl’ Does to Your Health” (Miller, 2026).

Google doesn’t help when its algorithms rewrite titles. The “What Staying Up Late” article appeared in Google search results as “Being a ‘Night Owl’ Has a Surprising Impact…” There are few causal terms more explicit than “impact.”

But the study was extraordinarily complicated with many acknowledged and unacknowledged limitations even beyond the correlational issue. For example, participants self-selected whether they were night owls, early birds, or something in between. Aside from a social-desirability bias that may lead some to unfairly claim early-bird status, participants could opt to say “don’t know” which the authors strangely placed into the in-between group.

Another study that drew from the same UK database removed the “don’t know” respondents. This study interestingly showed that night owls have superior cognitive function (West et al., 2024)—does staying up late make you smarter?

Night owls are being encouraged to get better sleep, eat better, and quit smoking. Although these are good general suggestions for anyone, it bears noting that both night owls and early birds had overall “favorable” heart health (with average scores of about 65 and 68 out of 100, respectively) and that early birds actually scored worse than the in-between group on 5 of 8 health indicators. Night owls also scored better than everyone on blood pressure despite some coverage claiming the opposite (Carefoot, 2026).

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Remote Workers

With so many recent headlines stating that remote work “hurts” or is "worsening” or otherwise diminishes mental health (Cerullo, 2026; Stark-Elster, 2026), it’s hard to infer anything other than a cause-effect connection. And yet—you guessed it—the cited study is correlational (or observational).

The pandemic-era study didn’t even compare remote and non-remote workers (Emanuel et al., 2026)—it compared those in jobs that could be done remotely (“remotable”) and those in jobs that usually could not (“nonremotable”). There are so many caveats and issues worth discussing that I’m relieved someone recently beat me to it. Writing for Reason, Brown (2026) bluntly addressed several “alarm bells.” Needless to say, there are other possible interpretations of the results, which Emanuel and colleagues acknowledged near the end of their article.

Although the common recommendation makes sense for remote workers to avoid social isolation, remotable workers had higher mental-health scores than nonremotable workers before the pandemic. Once the pandemic fades further into the past, potential remote-work mental-health benefits may again show themselves.

Time Buyers

A group of researchers has contended that spending money to save time “promotes happiness” despite almost all their many studies being correlational (Whillans et al., 2017, 2025). The research is circulating again on social media with cause-effect language which caught my attention.

A curious feature of the original 2017 report is that I could not find the exact wording of the time-buying item. Popular press coverage mentioned housekeeping and household maintenance. The New York Times headline suggested to “buy more takeout” and “hire a maid” (Chokshi, 2017).

But what exactly were the thousands of participants asked? Were they provided with time-buying examples like the maid idea?

Whillans and colleagues (2017) tried to address the correlational limitation by running something closer to a randomized controlled trial. The researchers gave $40 to each of 60 participants twice, once for a material purchase and once to buy time. The time-buying condition importantly yielded higher happiness scores, but aside from the limitations of a within-subjects design without a true control group, the participants did not spend their own money and were mostly female, married, and affluent which may limit generalizability.

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In the more recent article “Buying (Quality) Time Predicts Relationship Satisfaction” (Whillans et al., 2025), the use of the term “predicts” in the title and throughout was a noticeable language improvement over “promotes.” Several studies again used correlational designs.

But this time, the researchers also ran a randomized controlled trial to study the effects of recalling a time-saving purchase (vs. a material purchase). The results showed no difference in relationship satisfaction. Furthermore, the 2017 research conveyed an apparent boundary on the potential benefits of time buying. The authors shared that among people who spent more than “$101 to $200 USD” per month, more time buying predicted lower happiness scores, which seems to rule out a maid.

In Sum

All these studies were truly impressive undertakings with super-large samples and creative and sophisticated methodology. I did not have space to elaborate on their strengths and insights.

But as persuasively as many popular press authors and even some researchers suggest otherwise, correlation does not mean causation. I tell my students it’s the curse of the correlation. There’s no way around it. I empathize with correlational researchers and science journalists who want to say more.

To be clear, I’m not saying you should hoard your savings if you can afford weekly maid service. And I’m not promoting staying up late or being a loner—criticisms or concerns toward at least some night owls and remote workers may be warranted. I’m suggesting greater care in communicating the science to improve understanding and prevent negative stereotypes about these groups. It is definitely worth considering the suggestions the researchers provided to maintain or improve physical and mental health.