Jeffrey Rosenthal would not describe himself as a superstitious man. As a professor of statistics at the University of Toronto, he has always leaned on hard data from which to glean patterns and trends, and to test hypotheses. However, with his birthday falling on Oct. 13, he wanted to know if he was born on the day of the week associated with bad luck. In the late ’90s, Rosenthal had written a preliminary computer calendar program that he used to calculate the day he was born. “Oh that’s interesting,” he recalled saying. “That’s on a Friday.” Rosenthal was aware of the superstition: Friday the 13th has long been considered an unlucky day. He considered if those who believed in the superstition would assume that he was destined for a life filled with bad luck. It made the superstition feel “more personal,” he said, and indirectly sparked an idea down the line for a study. In July, he and co-author Jennifer Dmetrichuk released a paper titled “Friday the 13th, Full Moons, and Holiday Blues: Ontario Death Date Distributions,” published in Chance, a data-based quarterly magazine. The paper analyzed whether there is any truth to the superstition: Are bad events more likely to occur on a Friday the 13th? Applying science to the superstition It wasn’t Rosenthal’s first foray into research on luck and superstition. In 2018, he published a book titled “Knock on Wood: Luck, Chance, and the Meaning of Everything,” which applied scientific acumen to the existence of chance and superstition. However, the study published this summer had been on his mind for “a while,” he said. “It’s one thing to say superstitions are wrong, but as a scientifically-minded person, I want to investigate them scientifically.” As part of a different research project with Ontario’s Office of the Chief Coroner that examined correlations between the COVID-19 pandemic and different mortality rates, Rosenthal found himself with a massive database of unexpected deaths at his fingertips. With the data in hand, Rosenthal saw an opportunity to run the stats on supposed superstitions. “I thought, that’s a good record of things that people might consider to be unlucky,” he said. He analyzed all recorded unexpected deaths in Ontario between 2009 and 2023 and observing whether there was an uptick in rate of deaths observed on Friday the 13th, Halloween and full-moon periods. Friday the 13th: just an ordinary day The results were “as we expected,” he said. The mortality rates observed on Friday the 13th, Halloween and full-moon periods were “close to the overall rate,” he said. “...It wasn’t that interesting research-wise.” However, researchers did notice some patterns in the data. “Over the winter months, including the holiday period, there were elevated deaths,” Rosenthal said, “because of the challenges of winter in Ontario.” Rosenthal said the finding wasn’t new to the medical community, but it was an example of detecting real patterns in data. “The real patterns are more interesting than making up superstition patterns that aren’t really in the data.” He added that there was no “scientific explanation” explaining why a particular date would be unlucky. “Why would Friday the 13th affect all these bad things happening? It’s just another day.” In fact, Rosenthal considers himself an example of why Friday the 13th is in fact, not an unlucky day. “I’ve generally had a pretty fortunate life,” he said. “If you really believed it, maybe I’d have really bad luck my whole life, but actually I haven’t.” Why superstitions persevere While eye-opening for some, Rosenthal said he isn’t sure that his study will change the opinions of those who do hold superstitions. Superstition brings its believers a sense of comfort, he said. “I think they illustrate that humans have a sort of need to find reasons for things,” Rosenthal said. “It’s not enough to say that someone randomly died or randomly won the lottery ... it has to be because of some superstition, some good luck charm, some unlucky day and somehow that gives a lot of people a sense of comfort.” Rosenthal also said confirmation bias also plays a role into why superstitions like Friday the 13th may persevere. “Any time something bad happens on a Friday the 13th, that proves that there’s truth to the superstition,” he said. “Whereas (if) something bad happens on another day, or something good happens on Friday the 13th, maybe they won’t really notice that.” He advised considering the evidence behind superstitions. “Is there any scientific logic ... or is it just something I built up in my head and then I notice the patterns, even if they’re not really there?” he said. That being said, Rosenthal recalled a time in his life where he fell prey to superstition, through a bet he made with a friend on the outcome of the 2016 U.S. presidential election. He had originally bet Democratic candidate Hillary Clinton would win, but his friend enticed him into changing his answer by offering a two-to-one odds. “So I took those odds, just $1 to $2, and then Trump won, so he had to pay me $2,” he said. “And then I got this weird feeling like maybe it was because I made this bet, maybe that somehow had an effect on the election.” He acknowledged that while the feeling didn’t make sense logically, it “struck home” for him as to why people believe superstitions. “You find yourself thinking that way, that there’s these magic connections.”
