In an era where medical advice often arrives wrapped in breathless Silicon Valley hype, Rohin Francis offers a masterclass in skepticism disguised as a six-year shoelace experiment. By turning a mundane daily annoyance into a rigorous, randomized controlled trial, he exposes the vast chasm between anecdotal claims and actual evidence, proving that the scientific method is as vital for tying knots as it is for curing diseases.
The Hierarchy of Evidence
Francis begins by dismantling the low-quality data that plagues both alternative medicine and nutrition science. He contrasts the "crappiest form" of evidence—the case series—with the gold standard of research. "Observational first, the crappiest form is the case series," Francis writes, noting how pseudo-scientific practices often cherry-pick anecdotes to prove ineffective therapies work. He argues that these studies prove nothing, sitting at the very bottom of the evidence pyramid. This framing is crucial because it immediately establishes a baseline for critical thinking: if a claim relies on stories rather than data, it fails the first test.
He then moves through the hierarchy, explaining why cross-sectional studies and prospective cohort studies often fail to establish causality. "You can't establish causality from an observational study," he notes, using the example of diabetics who run less; the lack of exercise might be a symptom of foot pain, not the cause of the disease. This distinction is often lost in public discourse, where correlation is routinely mistaken for causation. By breaking down these study designs with such clarity, Francis arms the reader with the vocabulary to spot flawed logic in headlines about diet, exercise, or new health fads.
"If you're being sold or prescribed something that will go inside your body or purports to heal what ails you, you must insist on an even better level of evidence than this."
The Shoelace Randomized Controlled Trial
The centerpiece of the piece is Francis's own six-and-a-half-year experiment, a randomized controlled trial (RCT) conducted on his own feet. He assigned one foot to the "new" shoelace technique and the other to the "old" method, swapping sides annually in a crossover design to control for individual foot differences. "I randomized one of my feet to be the intervention arm of the study and the other foot to be the control arm," he explains. This self-experimentation, while humorous, is a serious demonstration of how to isolate variables. He even acknowledges the limitations of his "triple-blinded" status, admitting he couldn't achieve true blinding without a dedicated administrator.
The results were definitive in their ambiguity. Over 149 total instances of untied laces, the new technique resulted in 70 untyings versus 79 for the old method. "The new technique caused 70 bums and the old technique 79," Francis reports. However, he refuses to overstate the finding. "This is not a statistically significant result," he warns, noting that such a difference could occur by chance 20% of the time. This is a powerful moment of intellectual honesty. In a media landscape that rewards sensationalism, Francis explicitly rejects the temptation to cherry-pick a single year where the new method looked superior, choosing instead to present the full dataset.
Critics might argue that a sample size of one person (even with two feet) is too small to draw any meaningful conclusions about shoelace physics. However, Francis anticipates this, using the experiment not to prove the knot works, but to illustrate the standard required for medical interventions. The point isn't the knot; it's the rigor.
The Cost of Bad Evidence
The broader implication of Francis's work is a critique of how we consume health information. He observes that neither shoelace technique has harmful side effects, which is why the lack of statistical significance doesn't matter much for footwear. But the stakes are higher for medical treatments. "Often I'll see breathless promotion of some wacky treatment from often Silicon Valley type believers which has only been tested on mice," he writes. He urges readers to demand better evidence before accepting claims, whether they come from "goop, chiropractors, or a medically qualified doctor."
Francis emphasizes that critical thinking is a skill built through practice, not passive consumption. "The best way to build that up is with regular practice, not just passively watching clowns on the internet like me," he admits. This self-deprecating tone disarms the reader, making the lesson on logic and probability feel accessible rather than academic. He suggests that the ability to distinguish between a case report and a randomized trial is a fundamental defense against misinformation.
"Don't be afraid to ask what is the evidence for this. If they give you a bunch of anecdotes, you know that this isn't a proven therapy."
Bottom Line
Francis's argument succeeds because it uses a trivial subject to illuminate a profound truth: the scientific method is the only reliable tool we have for navigating uncertainty. While the shoelace trial itself is a whimsical outlier, its application to real-world health decisions is urgent and necessary. The piece's greatest strength is its refusal to oversimplify, forcing the reader to sit with the discomfort of "not statistically significant" results in a world that demands certainty.