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Fill a conference room with 250 20-something Americans chosen at random and chances are September will be the most common birth month for the group. Now fill that room with the top 250 women’s and men’s LPGA and PGA tour pros this season and the results are going to be completely different.

I compiled every publicly-available birthday for the professional golfers ranked in the top 125 of the Official World Golf Rankings (OWGR) or Rolex Women’s World Golf Rankings, and roughly one out of nine will celebrate their birthdays sometime in November.

Yet, according to data released by the Centers for Disease Control and Prevention (CDC), November had the second-lowest observed birth rate of any month in the calendar year, among births in the U.S. in 2019. The most popular birth months for Americans in 2019 were August (an estimated 341,685 births), July (333,646) and September and October (roughly 325,000), while the calendar’s shortest month, February, predictably had the fewest births (279,963).

April and November were the only other months with fewer than 300,000 estimated births, with more than 298,000 each.

The most common day of the week for Americans to be born in 2019, by the way, was Tuesday, followed by Thursday. And according to research by Matt Stiles, a data journalist for the Los Angeles Times who produces data visualizations for his website The Daily Viz, nine of the 10 most common birthdays for Americans born from 1994 through 2014 fell in September. Sept. 9 led the way, with an average of 12,301 births.

Matt Stiles' heat map for birthdays.

Matt Stiles' heat map for birthdays.

Stiles has produced some of the most comprehensive research and compelling data visualizations into birth rates in the U.S. I spoke to Stiles over the phone for insight into the birth date data of the world’s top pros and given the number of elite South Korean golfers, especially on the LPGA Tour, Stiles’ time as a foreign correspondent in South Korea proved beneficial.

So what’s going on here with the birthdays of the world’s best golfers? Is there something deeper revealed in the data, such as more NHL draft picks being born in January, or is this simply a statistical blip?

I’ll get more into the potential whys soon, but first, here are some of the takeaways shown by birth rate and birth date data:

  • Among the 32 South Korean golfers examined, half were born from July through October, while just five were born from November through February. That's likely because of Chuseok, a holiday with lots of shared meals and downtime.
  • Less than five percent of the golfers examined were born in December. According to Stiles’ research, Dec. 24, 25 and 26 rank among three of the six least-common birthdays for Americans, but five of the 30 most-common birthdays fall in December. On a large scale, Stiles cites Christmas as the explanation for the former and the desire to have a child before the end of the tax year as the explanation for the latter.
  • Among the 77 American golfers examined, November (10 birthdays) was the most popular birth month, but there was little variation from month to month, with nine of the 12 months having at least six players born in the month. March (two), January (four) and December (five) proved to be the exceptions.

Even though November is the birth month of the world’s No. 1 men’s golfer, Jon Rahm, as well as top-50 men’s and women’s players such as Joaquin Niemann, Max Homa, Mackenzie Hughes, Ariya Jutanugarn, Celine Boutier, Hinako Shibuno, Madelene Sagstrom and Leona Maguire, based on current birth rates in the U.S., there’s a potentially smaller pool of elite golfers who were born in November compared to other months.

There were an estimated 298,086 births in the U.S. in November 2019, compared to 341,685 births in August 2019, according to the CDC, and that difference represents a November-to-August increase of nearly 45,000 children, or roughly a 14.6-percent increase.

Among the 236 players examined — not every golfer examined has a birthday that is publicly available — 27 golfers were born in May, the most of any month, followed by July and November, which each had 26 top-125 men’s or women’s golfers born in the month.

Of course, golf is truly an international game — as of Nov. 15, half of the top 50 golfers in the OWGR were born outside the U.S., as were 39 of the top 50 female golfers — so we can’t only look at monthly birth rates and trends in the U.S. for possible explanations as to when elite golfers were born, and why.

“I suspect that of that list … maybe 65 percent or 70 percent are ‘Western,’ like European or Australian or American,” said Stiles, the journalist for the Los Angeles Times.

Stiles continued, as he described countries that have what could be described as a Western culture, “They might have similar societal calendars that prompt them to fit more in the graphic that I made, specifically Christmas. So people are off work for Christmas and you see that in the United States, the most common birthdays are in September, which correlates directly to time off in mid-to-late December for Americans.

“If you look at the gestation period of how long it takes a child to be born, and then you cycle back [to] Christmas, you get mid-September as the most common (birthday).”

Stiles’ research of two decades’ worth of American birthdays found that 10 of the 11 most popular birthdays in the U.S. fall in the date range between Sept. 9 and Sept. 20, which roughly correlates to a conception date range of Dec. 17 through Dec. 28, when many Americans and citizens of other countries with Western cultures are off of work around the holidays.

However, despite the relative popularity of September births in the U.S., among the birthdays of the golfers examined, September (15 golfers born that month) ranked ninth out of the 12 months, ahead of only March (14 golfers) and December (11). September’s relative standing compared to the rest of the months is a worthwhile reminder of the global nature of golf, especially the top female players in the world.

“Look at South Korea, for example,” Stiles said. “The biggest holiday that I can remember there is called Chuseok, which is kind of like a festival and that’s usually [in] October, and so that could be a reason why you see the July births, because it’s just that time-home-with-family calendar is moved up a few months…

“I bet if you isolated the group of June, July births, a lot of them are the South Korean women.”

Among the 236 golfers examined with publicly available birthdays, 32 are South Korean. Thirty-nine of the 125 female golfers in the world are South Korean. Like Stiles predicted, July was the most common birth month among the South Korean players examined.

Five out of the 32, or almost 16 percent, were born in July. Four other players were born in August, and 12 of the 32 were born during the summer months.

“The takeaway, I guess, that I would say to you is that it really is dependent upon the societal calendar for when these births happen,” Stiles said, “so you’re gonna see a different disbursement of births when you look at global players as opposed to just the American ones, or just Western ones, the ones that participate in the same calendar that Americans do.”

Among the 77 American players examined, November (a month-high 10 golfers) and February (seven golfers) stand out as months in which relatively high numbers of elite golfers were born.

Due to February being the shortest month in the calendar, the CDC estimated that 279,963 children were born in the U.S. in February 2019, which was roughly 19,000 fewer children than in the months with the next lowest totals, November and April.

And not only are there more elite American golfers (as defined above) who were born in February than in January, March, April, August, September, October or December, but February also marks the likely month of conception for the 10 American golfers who were born in November. Perhaps Valentine’s Day, smack-dab in the middle of February, could be one potential layman’s explanation as to why there’s a relative flurry of November birthdays among the world’s best golfers.

Or, perhaps the noticeable number of fall birthdays – 49 of the 236 golfers examined, or almost 21 percent, were born in October or November – could be traced to all of the time spent indoors during the winter. Maybe the month-high 27 birthdays in May could be explained by the end of the summer, or the start of the traditional academic calendar.

“There may be some other explanation for it,” Stiles said. “There may be that winter has something to do with it, as opposed to just time off. You know, people are indoors more. There are other factors. It’s not just Christmas, right?”

There’s also a case — both a statistical and practical one — to be made that any trends in the birth months of elite golfers compared to those of the world’s population can be chalked up to sample sizes and randomness.

“There’s not a huge amount of variance month to month,” Stiles said. “I mean, there’s an obvious variance day to day if you look at that graphic. I can’t remember the specific numbers but it’s like, the other months are five percent fewer births or something. It’s not as if September has some huge spike. It just fights above its weight in terms of the number of days in the month and the number of births. But there are a lot of births in other months, too.”

There’s also some level of self-selection in specific dates of birth, as expecting American parents push for certain days and avoid others.

December 28, 29, and 30 all rank among the 30 most common birthdays in Stiles’ analysis of two decades of births in the U.S. The least-common birthday was New Year’s Day, followed by Christmas Eve, the Fourth of July, Jan. 2 and Dec. 26.

That isn’t a coincidence.

“You see, for instance, a spike in Valentine’s Day births and a decrease in births right around Christmas, right around Thanksgiving, because people just choose not to have a C-section that day,” Stiles said. “And the same thing, you see a spike right at the end of the year, like the 27th, 28th, 29th of December, because you want to have that child before the next tax year.”

The holidays are approaching and for most of us, that means time off work, time spent at home with family and friends, and the exchanging of gifts. They could also mean the next wave of great golfers is either being born, or nine months from being born.