Think about the items you put in your cart during your last trip to the grocery store. Recall the new fast-food value meal you saw in a commercial, or the app you use to check your bank account balance, or the packaging of the shampoo you purchase for your dog. It’s extremely likely that sometime before any of these products saw the light of day, a half-dozen or so strangers got together, sat down in a conference room with a one-way mirror, and debated their merits in exchange for a couple hundred dollars each.

We now live firmly in the age of big data. Every link we click is tracked and cataloged. We rate our Uber drivers and the things we buy on Amazon and the cleanliness of airport bathrooms. The movies and TV shows we’re prompted to stream on Netflix are based on algorithms that analyze everything we’ve ever watched before. But when designers and marketers need to come up with new ideas or vet products before trying to sell them, they still turn to the same lo-fi method that’s been in use for decades: putting a bunch of people in a room and having them hash it out as part of a focus group.

Focus groups might seem like a throwback — they came to prominence in the middle of the last century — and their demise has been predicted many times over in recent years. But for as many times as they’ve been declared dead, a victim of ever-improving digital analytics, they haven’t gone anywhere. In 2017, $2.2 billion worldwide was spent on conducting focus groups, according to the trade group ESOMAR, with $809 million of that coming in the US.

In the 1950s, focus groups famously led Mattel to make Barbie one of the first adult-looking toy dolls, and in 2014, they convinced the company to introduce a new, “curvier” Barbie to appeal to a more varied audience. Today, corporations use focus groups to study and sell everything from frozen foods to summer blockbusters. Political parties use them to hone campaign messaging, as do US government agencies concerned about public reaction to policy changes. Law firms even use them when trying to gauge how juries will respond to an argument or line of questioning.

Like most of us, I’ve spent my life consuming products shaped by focus groups. So a few months ago, I decided to become an active participant in them. After entering my name in recruiting databases and filling out countless surveys, I took part in seven different groups, offering my views on unique beverages, novel insurance concepts, and new snack flavors. I’ve been asked if I prefer the taste of formula A or formula B, but I’ve spent much more time answering questions that are far less straightforward: which stock images, for instance, most accurately reflect my relationship with a brand. I’ve heard participants contradict what they said a moment beforehand; I’ve met regulars on the focus group circuit who routinely sell their opinions as a side hustle.

All this has left me with a question I keep asking myself as I fill out survey after survey. Focus groups have a hand in designing so many of the things we own, and the cost of conducting them gets passed on to us in the prices we pay for these products. But are they a unique window into our tastes and innermost desires, or an elaborate waste of time and money?

I started my search with help from a friend, a focus group regular for the better part of 10 years, whom I’ll call Claude (he’s asked me not to use his name so as to preserve his future earnings). He showed me the websites where I could sign up to receive recruiting surveys and suggested what sorts of answers could land me in studies: It’s good to say you’re responsible for the majority of your household’s grocery shopping, and that you’re open to trying any brand of a given product.

After filling out a few surveys, I began to get calls from recruiters, who would painstakingly confirm all my survey answers before inviting me to sessions that typically went for an hour or two and paid $100 or so. Often, they added, if I showed up early, I’d be entered into a raffle to win a cash bonus.

I never did win one of these raffles — one of a few trends I saw over and over again as I became a focus group regular myself. The rooms look like you might imagine: flavorless conference rooms with wall-to-wall mirrors at one end that you can just barely see through if you look at the right angle. The facilitators generally begin by asking everyone to go around and say a fun fact about themselves; they seem trained to reply to every comment, no matter how uninspired, with praise. The atmosphere is usually somewhere between that of a holiday office party and jury duty. People generally do make an effort, but there’s also a clear sense that everyone is mainly looking forward to leaving as soon as the hour is up, their obligation fulfilled, so they can grab their check on the way out the door.

While we might be shown ad mockups for new products or offered flavors to taste, vague, open-ended exercises are the real bread and butter of these sessions. I was often asked to relate personal experiences I’ve had with a product, or describe scenarios that might prompt me to buy it. More than once, I was asked to close my eyes and visualize scenes I associate with a brand. In theory, these kinds of activities are meant to probe for emotions or product associations we might not even realize we hold.

This is a tactic that dates all the way back to the accidental invention of the focus group in 1941. As Liza Featherstone details in her fascinating history Divining Desire: Focus Groups and the Culture of Consultation, the idea came out of Columbia sociologist Robert Merton’s impromptu visit to a test airing of This Is War, a US Office of War Information radio program meant to counter Nazi propaganda. His Columbia colleague Paul Lazarsfeld had given the test listeners a device with buttons to record whenever they liked or disliked the broadcast — itself a major market research innovation — while another researcher followed up by asking the audience why they had pressed the buttons at various moments. “[Merton] began to observe the interview keenly, and to send Lazarsfeld notes,” Featherstone writes. “Lazarsfeld asked Merton, if he thought he could do so much better, why not try it himself?”

Merton did so, and over the course of World War II would go on to develop what he called “The Focused Interview”: a discussion emphasizing the “subjective experiences” that shape a person’s response to a particular item, whether a radio program or box of cereal. Rather than collecting raw numbers on how many people preferred one product or the other, Merton sought to dig into “the relevant personal context, the idiosyncratic associations, beliefs, and ideas” that quietly colored people’s preferences, often without their explicit knowledge. He felt it especially important to include open-ended questions so participants could move the conversation in directions meaningful to them, and to drill down to the underlying, sometimes subconscious why of their opinions — not just the what.

The interviews, borrowing heavily from psychology and anthropology research methods, contrasted sharply with the statistical methods used in market research at the time. Madison Avenue ad firms were soon hiring Merton and others to hold focused interviews — usually with a group of people at once — to gauge what consumers wanted to buy, and how to sell it to them.

This era spawned a flurry of Freud-flavored focus group success stories of varying plausibility that are nonetheless celebrated to this day. Ernest Dichter, the psychologist who’d coin the term “focus group,” used them to determine that people supposedly preferred borrowing money from loan sharks to banks because they felt judged by bankers’ stern authority — and recommended that banks offer checking accounts with overdraft, so people wouldn’t have to come in to ask for a loan.

Focus groups led another psychologist, Herta Herzog (the inspiration for Mad Men’s Greta Guttman), to proclaim that for men, cars represented the ultimate fulfillment of repressed sexual desires, pushing auto companies to put out increasingly sexualized advertisements throughout the ’50s.

Focus groups still seem to be preoccupied with emotion, but the way these findings are incorporated into market research has become a whole lot more rigorous over the years. “We always recommend to all of our clients that they do both qualitative and quantitative research,” says Andrew Tuck of ARC Research, which conducts polling and statistical analysis alongside focus groups. “You can’t talk to 10 people outside St. Paul and make a good decision based on that.”

Like many in the industry, he feels that focus groups can be useful for generating hypotheses at the outset of a project so they can later be tested quantitatively, rather than for ranking option A versus option B right before one has to go to market. As Kristen Miles of Branded Research puts it, “With new product development, companies often don’t even know where to start. We need people to tell us as researchers what we should focus on.”

If a client wants to run focus groups, ARC will carry them out with one of a few national panel companies: firms that host sessions, often in their own facilities, and recruit participants by emailing out surveys. “Recruiting participants is usually the most expensive part,” Tuck says, explaining that finding the right people — often based on whether they already buy the client’s products, or those of a competitor in the same category — can lead to a total cost of around $10,000 per session for the client. After finding the right people who promise to show up at the right time, the panel company will typically hold sessions in a few major US cities. The clients themselves will often gather behind the one-way mirror, bowls of snacks and popcorn at hand, to watch the proceedings.

“It’s like you’re looking at ants from above,” says David Reischer, who used focus groups in deciding on a domain name for his website LegalAdvice.com. He remembers being fascinated watching people pick apart various names his team had come up with, unaware that the creators of the list sat feet away behind a thin layer of glass and aluminum.

Steve Thomas, a former executive at Edible Arrangements, says he liked to see participants’ behavior from the moment they walked in the door. “Tasting the product always generates a lot of robust discussion,” he says. “But as a client, we are really watching for responses much earlier. How did they respond to the idea of the product? What was their visual response to it and its packaging?” For him, this sort of spontaneous behavior is more valuable than people’s answers to scripted questions — it’s a deeper look at the sorts of opinions they might not even think to share on, say, a structured survey.

This fits with what Tuck describes as the main purpose of the focus group: to get people talking. “If you’re doing a good focus group, it’s not a question-and-answer session,” he says. “You don’t really care about the answers. What you care about is observing natural conversation.” Listen to enough ordinary conversation, the theory goes, and companies will hear ideas they wouldn’t have conceived of on their own.

But this is a hotly contested point. “In my 40 years working in design and innovation, alongside some of the most brilliant minds in the business, I have never seen innovation come out of a focus group,” wrote designer Gianfranco Zaccai in an anti-focus group polemic a few years ago. “Let me put it more strongly: Focus groups kill innovation.”

When I spoke to Zaccai, he qualified his views, allowing that listening to a product’s users can be extraordinarily helpful in giving a product designer insight into how their designs are actually used. However, he said he’s seldom gotten truly novel ideas from users, and when he’s come up with a hit idea on his own, focus groups have tended to reject it even when it’s gone on to huge success in the actual market. When he debuted the legendary Reebok Pump to a high school basketball team in the 1980s, for example, the players laughed at the idea, turned off by the shoes’ weird appearance; the sneakers are now acknowledged to be among the most influential in Reebok’s history.

This sort of critique — that innovation is the province of the professional, rather than the laypeople who make up focus groups — has been around almost as long as focus groups themselves. It came to even greater prominence in the 2000s, propelled by people like Malcolm Gladwell (who railed against focus groups in a 2005 speech) and Steve Jobs. “It’s really hard to design products by focus groups,” Jobs famously said. “A lot of times, people don’t know what they want until you show it to them.”

At least in my focus group experience, there’s some truth to this. I’ve been part of several groups that tear apart a proposed product, often for good reason. But afterward, when the facilitator asks for alternative ideas, we’re all silent.

One key benefit of focus groups, I was told several times while reporting this article, is that they expose designers and marketers to the relevant context of real people’s lives. But how good are we really at talking about ourselves honestly in front of groups of strangers? I’ve tried to make a sincere effort during my focus groups, but when asked exactly how often and why I buy things like frozen dinners or junk food, there’s always a strong temptation to lie. I don’t think that’s just me.

For many people, it can also be tough to air a dissenting opinion during a focus group. A particularly strong voice often sways everyone’s opinions, and psychologists consistently find that most people, despite what they might claim, prefer to blend in with the group rather than stand out on an island.

You don’t need to do many focus groups to see groupthink in action. During one focus group I did, the moderator passed out design mockups for a new product and asked each of us to rank them from most to least appealing. We each laid them out in our preferred rankings, but then something interesting happened. To my left, there was a hip-looking guy who happened to work in an industry adjacent to the product. He also considered himself something of an authority on matters of aesthetics and went on for some time about the designs. Then several people around the table reordered their choices and justified why they’d done so.

The moderator tried to emphasize that differences of opinion were expected, and even preferable, but it was striking to see more than one participant change their answer to mirror those of a perfect stranger — and then seemingly tell themselves it was what they’d thought all along.

Some view this as a feature of focus groups, not a bug. Tuck, the market research professional, told me it’s part of what his field refers to as “group effects”: the ways people’s behavior changes when they know they’re being observed and judged by everyone else. “Ultimately, people behave in groups. Consumers are groups of people. Voters are groups of people,” he said. “The lies people tell themselves about themselves, or tell their community — that’s the exact kind of stuff we want to hear.”

The idea is that we’re fake in focus groups the same way we’re fake in real life. Our social behavior is who we really are — at least insofar as it matters to retailers. In a world of abundance, what we ultimately choose to buy often hinges on how a product makes us feel, how it makes us view ourselves, and how we imagine it affects how others see us. This is why focus groups spend so much time digging into the emotional. They want to capture our most authentically fake selves: the selves we declare ourselves to be with the clothes we wear and the foods we eat and the vacation photos we post to Instagram.

Still, focus groups are rife with another type of deception, one that starts before participants even walk in the door. Ever since a 2004 New York magazine article that advised readers exactly how to lie to qualify for as many groups as possible, industry professionals say they’ve been fighting the scourge of what they call “professional” respondents, who’ve made focus groups into a lucrative side gig. By his own accounting, my friend Claude has done 95 focus groups for a total of $10,740 over the past decade. The trend has only become more common in the internet era, with focus group tips from sites like Stay a Stay at Home Mom; more than once, Claude’s told me, he’s struck up conversation with a co-participant in the elevator after a focus group and found that they, too, are a regular.

There’s a whole lot of gray area to work within when filling out the surveys. You can, for example, rate your personality as “extremely outgoing” rather than the more accurate “somewhat outgoing,” and you can indicate that you plan to buy a car sometime in the next year, when in reality it might be more like two or three. Fill out enough surveys and you learn that these are the sorts of little lies that get you into groups.

One might blame respondents for exploiting the system, but I frequently got the sense that the panel companies are in on it too. Claude told me about a screening call he got a few months ago from a recruiter at Schlesinger Group, a market research firm. “They asked if I had been to a financial seminar before and I said yes,” he told me. “She said, ‘Did you mean to say no?’” He changed his answer, was invited to join a group, and made $200.

When I reached out to representatives of the company for comment, they seemed concerned, and described the protocols they have in place to these sorts of events. “For this specific part of the process, we perform an initial screener, re-screener, and, for an in-person project, a facility onsite screener,” said Terri-Lyn Hawley, a VP at Schlesinger. “These are all managed by different teams, as well as randomly monitoring phone calls, to mitigate the risk of something like this happening.”

But I saw this pattern with other panel companies I interacted with, and it’s one Liza Featherstone experienced when participating in focus groups as part of the research for her book Divining Desire. The reason is simple, she explained to me: The longer it takes to fill a group, the higher the cost. As a result, panel companies pressure their recruiters to find participants as quickly as possible — and force them to blur the line between finding members of the right demographic and coaching people into saying the right answers. There are other signs that panel companies are well aware of regulars. Another friend of mine, who started doing focus groups over the past year, was recently given a W-9 form from Schlesinger because she earned more than $600 in annual income from them.

For Featherstone, though, the extent to which all this really matters is debatable. “Focus groups are not a scientific and quantitative method of gathering knowledge anyway,” she says. “So the fact that some people are participating frequently really doesn’t matter.” A focus group, in other words, is a case study, not a scientific survey. It’s a limited interview that nevertheless may illustrate something about a bigger whole. It’s not an ideal way to gather accurate data on, say, what percentage of people prefer a new flavor of latte to the original, but it might be a good way to unearth useful truths about how people decide to try a new flavor of latte, and what role that flavor might play in their lives.

In exchange for these details about our private lives over and over, we focus group regulars get something quite valuable too, apart from the money. During the very last group I did for this project, carried out by a cable company, I had a realization. For more than an hour, I was granted the privilege to complain about one of our most reviled consumer services. Normally, we have to navigate complex automated phone systems just to talk to anyone at a cable company; here, professionals spent time politely listening to us rant about deceptive fees and frustrating customer service so they could write reports to executives about it.

As I sat there airing my trivial grievances to a captive audience, I discovered something that surprised me but probably shouldn’t have. Perhaps the most authentic fact about consumers that focus groups elicit is this: It feels good to talk. It feels good to be heard.

Hope everyone enjoyed 2016, because this year is going to last one second longer than usual.

No, really: On December 31, New Year’s Eve, the world’s timekeepers will add in a “leap second” to keep all our clocks in sync with the Earth’s rotation. They do this because the Earth technically takes a bit longer than 24 hours to complete a full rotation (86,400.002 seconds, to be exact). So a leap second gets added every few years.

In fact, this adjustment has actually become quite common: Ever since leap seconds started getting added in 1972, fully 27 out of 44 years have included one.

For those living on the US East Coast, this year’s leap second will occur at 6:59:59 pm EST on December 31. Official clocks will hit 6:59:60 before rolling over to 7:00. If you feel like celebrating, you can. If not, well, this probably won’t affect your life all that much. A previous leap second in 2012 caused a glitch in the software running Reddit, Gawker, and other websites, but systems are far better prepared this time around.

What’s really neat, though, is the science behind the leap second. Earth’s rotation continues to change subtly over time, due to a variety of factors from tidal friction to melting ice caps — and that makes keeping time far more challenging than you might expect. Here’s a guide.

1) When does the leap second happen?

On New Year’s Eve — though the exact time varies from place to place. For those living in Coordinated Universal Time — the world’s official time standard, based off atomic clocks and used to calculate the times around the world — the leap second will happen on December 31 just after 23:59:59. Clocks will move to 23:59:60 before moving on to 00:00:00 the next day. Revelers in the United Kingdom will have to adjust their New Year’s countdown accordingly.

If you’re living in the East Coast United States, the leap second will happen on December 31 at 18:59:59. If you’re living on the West Coast, it happens at 15:59:59. And so on.

2) What should I do with my clocks?

Nothing. People who write timekeeping software have had to go to lots of trouble to make sure the leap second doesn’t cause any glitches, but you’re all set. Enjoy the extra time and contemplate the cosmos.

Devices that set their times automatically — like phones and computers — will adjust on their own. And you really don’t have to worry about your other clocks, because a one-second difference between their time and official time is probably too small for you to notice.

3) Why do we need a leap second?

This is where things get interesting. As it turns out, all sorts of factors, including tides and melting glaciers, cause the rate of Earth’s rotation to vary slightly over time (more on that below).

“Lots of people think the Earth’s rotation is a simple, 24-hour thing,” Steve Allen of the University of California’s Lick Observatory told us last year. “But weather in the atmosphere, in the ocean, and in the core of the Earth make it complicated.”

Historically, this variation didn’t really matter, as the world’s official clocks were based off Greenwich Mean Time, which in turn is based off the time when the sun is highest in the sky in Greenwich, London. We set our clocks based on the position of the sun (and thus, the rotation of Earth) and didn’t really notice when it varied by a fraction of a second.

In 1967, though, most countries switched over to Coordinated Universal Time (UTC), which is based off atomic clocks that run with extreme precision. (The basis of their seconds is the frequency at which electrons surrounding an atom jump from one energy level to another.)

That created a problem: This new standard defined a second as 1/86,400th of an average day — but that was based on the estimate of an average day in 1900. The problem is that days have generally been a bit longer since then, as the Earth’s rotation has slowed, and so a discrepancy has formed between solar time and official time.

The difference is very small, amounting to less than a second per year. But if we didn’t start using leap seconds to account for it, the two clocks would now be nearly 30 seconds apart. Eventually, over centuries, this could lead to the sun reaching the highest point in the sky minutes after official noon — and over millennia, the gap could get hours long.

So as a solution, timekeepers in the International Telecommunications Union (ITU) — the United Nations agency that manages UTC — stick in a leap second whenever the difference between the two clocks threatens to exceed 0.9 seconds. They determine when to do this based off the observations of astronomers who carefully measure Earth’s rotational speed by looking at distant quasars in the sky/universe:

The official rules dictate that leap seconds can be inserted up to twice a year (on June 30 and December 31), always at 23:59:60 UTC. (The last leap second occurred on June 30, 2015.) The timekeepers can also subtract a second, but that has never been necessary so far, as Earth’s days have generally been longer than 86,400 seconds, not shorter.

4) Are some timekeepers opposed to the leap second?

Yes! As you might imagine, this sort of ad hoc process bothers some people who devote their lives to keeping time as precisely and consistently as possible — and it presents a practical problem for people who write software that involves time, which is to say virtually all software running on every computer.

Leap seconds were originally devised with sailors in mind, who at the time used the position of the stars to navigate and thus wanted Earth’s rotation to roughly match up with official time. Now, however, ships use GPS — and the GPS time system, in fact, doesn’t use leap seconds at all, so it’s constantly drifting away from both UTC and solar time.

As such, in 2005 American members of the ITU proposed to abolish the leap second. Their plan called for leap hours rather than leap seconds, allowing UTC to drift as much as an hour away from solar time. In practice, this would have decoupled the two clocks, as it’d take thousands of years for an entire leap hour to be necessary.

The proposal wasn’t formally submitted, but other countries have presented similar ideas, and the debate has continued within the ITU over the years.

5) Why does Earth's rotation vary over time?

There’s a whole array of complex reasons why Earth doesn’t spin at a constant rate. Anything that alters the distribution of its mass affects its speed.

Long-term factor: tidal friction

Over the longest time scales, the main factor at play is a phenomenon called tidal friction. As the moon orbits Earth, its gravity pulls at our oceans, creating two bulges of water that rotate around the planet, called tides.

But these bulges aren’t oriented directly underneath the moon. They’re slightly ahead of it, in terms of the direction of Earth’s rotation. As a result, the Earth’s crust encounters just a bit of friction from this bulge of water as it rotates, slowing it down slightly.

Over time, this has slowed down the planet dramatically: About 4.5 billion years ago, it took the Earth just six hours to complete one rotation. About 350 million years ago, it took 23 hours. But over time, it’s grown by about one to two milliseconds every century.

Long-term factor: glaciers melting

The other big long-term factor is the melting of glacial ice. “During the last ice age, the weight of ice sheets in North America and Antarctica pushed mantle mass very slightly toward the equator,” Ryan Hardy, a PhD student in geodesy at the University of Colorado, explained last year. Over the past 12,000 years or so, though, that ice has melted, causing the land below it to spring back up very slightly (currently at rates of a centimeter or so per year in these polar regions).

This means there’s slightly more mass at the poles and less at the equator, bringing more near the planet’s axis. This causes it to spin a bit more quickly — and an average day to shorten by about 0.6 milliseconds every century. Climate change is projected to further shorten the length of a day by about 0.12 milliseconds over the next two centuries as glaciers melt even further.

Shorter-term factor: outer core activity

Over the course of decades, geologic activity within Earth’s outer core can speed up or slow down the length of a day by a few milliseconds. This layer of molten rock — situated between the solid inner core and the semi-solid mantle — rotates slightly faster than the rest of the planet. The flow of this liquid rock alters the transfer of momentum to the mantle and crust and, as a result, the Earth’s measured rotation speed. But this variation and its relationship to the Earth’s speed isn’t well-understood.

Even shorter-term factors: wind, tides, storms, and more

At shorter time scales, a huge variety of factors can alter the length of a day by around 0.2 to 0.3 milliseconds.

Seasonal changes in wind speed, for instance, can sap slight amounts of the planet’s rotational momentum. If the atmosphere as a whole is moving primarily from west to east, for instance, this effect will slightly slow down the rotation of the planet underneath it as it turns in the same direction. Ocean currents can do the same.

Tides also cause a number of distinct cycles in the length of a day — at 12-hour, daily, fortnightly, monthly, every six months, every year, and 18.6-year frequencies — by subtly changing the shape of the Earth. This is distinct from their longer-term tidal friction effect. The 12-hour variations, for instance, are due to each day’s two high tides and low tides. The longer-period variations are linked to subtler, longer-term cycles in tides that are caused by gravity exerted by the sun and Jupiter.

Finally, there are random, sporadic events — such as giant storms — that may alter the distribution of mass throughout the Earth enough to change its rotation speed. It’s been hypothesized that earthquakes could do the same, but that hasn’t been proven yet.

In the late 1970s, a spike in gas prices set in motion a stronger emphasis on aerodynamic design for American cars. That wasn’t an entirely new thing: When family cars were first becoming popular in the 1930s, most models were designed in a very curvy shape for fuel efficiency, like the Chrysler Airflow. But a steady decline in gas prices between the ’30s and ’70s meant that aerodynamics became a fairly small priority for US carmakers.

Once the price hike hit, American manufacturers started taking cues from designers in Europe, where higher gas prices had always encouraged curvy design. That design influence has stuck around ever since.

The video above shows how that big shift happened between the 1980s and 1990s — and how the world reacted when it did.

One of the most widespread superstitions in modern society is the idea that Friday the 13th is unlucky — a phobia that may stretch all the way back to 1780 B.C and the Code of Hammurabi.

We’re here to dispel it.

There have actually been a number of studies looking at whether enough unfortunate events occur on Friday the 13th to justify “friggatriskaidekaphobia.” None of them have turned up any good evidence that they do. Here’s a quick look at the data.

The evidence that Friday the 13th isn't unlucky

One of the first studies of Friday the 13th looked at traffic accident rates in a London suburb, and found that significantly more hospital admissions due to accidents did occur.

But that doesn’t necessarily mean Friday the 13th is unlucky. Others subsequently pointed out that the sample size (one town and 65 total accident-related injuries) was pretty small. Given that Friday the 13th is just an artifact of our Gregorian calendar and there’s no known mechanism through which it could cause bad luck, the data wasn’t strong enough to support such a claim.

A more plausible hypothesis might be that Friday the 13th itself doesn’t cause bad luck, but it does lead people to behave differently out of fear or anxiety, thereby causing things like accidents.

there’s no known mechanism through which it could cause bad luck

Subsequent studies, though, don’t support this idea idea either.

While a Finnish study found female drivers were more likely to get in accidents on the Friday the 13th, a follow-up found the correlation disappeared with better data and more controls. A German study similarly found that the number of accidents and errors that occur during hospital operations is pretty much the same on Friday the 13th as on other days.

A few other studies have looked at the very plausible idea that stock markets might perform more poorly on Friday the 13th — because of investors’ superstition — but surprisingly, they found the markets actually do slightly better, on average, than on other days.

The superstition might be widespread and deeply rooted, but there’s no real reason to believe Friday the 13th is unluckier than any other day.