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factorialfun t1_iym82w3 wrote

Really it has to do when the birthday cut off is for the sport. It differs for baseball, hockey, and soccer.

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desfirsit OP t1_iym8ca6 wrote

Yes, and between countries. But I thought I would just do something simple here (most countries probably use January 1 as the cutoff), and I think the fact that it shows up despite the coarse analysis shows the importance of the phenomenon.

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Pain_Free_Politics t1_iymb014 wrote

It might be more complicated but I’d be curious to see this data adjusted to ‘month of the school year’ rather than calendar year.

IE in the UK, a September birthday would be listed as a ‘month 1’ as it’s the first month in our school calendar, and how age for this sort of thing is calculated. I think varying school start dates by country explains a few of these random peaks, but it’s hard to be sure.

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enny_el t1_iyn2hl8 wrote

I often wonder about this - how birth month might affect academic or sporting performance. Someone must have done this research to some extent, surely? I'm from the UK, had kids in Mexico (where school year cutoff was December at least in our district) and now live in US, where it's October, but where so many parents try to game the system by holding their kids back that some districts are really strict on age/school start dates. It's fascinating.

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unblockablemid t1_iynfzkv wrote

Outliers by Malcom Gladwell is basically about this and has a section on how kids born at a certain time of year have advantages over others (in sport), as they're more physically developed, and are more likely to getting scouted. Highly recommend if this kinda thing interests you.

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Anachronism-- t1_iynku3k wrote

He’s done an update on his podcast recently. Now some parents are using his data to intentionally hold their Children back a year to give them an academic advantage. Enough to start skewing the data.

Edit - I don’t think gladwell came up with this idea but he did make it more mainstream.

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SolemnLoon t1_iynm9ng wrote

It would be easy to enough to adjust for birth year. Instead of just birth month, it would be number of months older than the minimum.

For instance, someone who turns 17 on Sep 1 of their senior year (12th grade) would be considered "0 months" old. The typical range would be 0-12 months if everyone was born in that year, but someone who was held back and turned 18 two months before their senior year started would be "14 months". Your range might be as much as 0-24 instead of 0-12.

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Anachronism-- t1_iynpcjf wrote

I listened to it a while ago but that sounds similar to what he ended up doing.

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classybroad19 t1_iyoz3ms wrote

He didn't, in the podcast he talks about the Canadian researcher's wife who noticed it.

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SolemnLoon t1_iynmqlr wrote

Yep... I loved that chapter. If the sports leagues are really interested in finding the best players regardless of birthdates, they could do a sliding cutoff that changes 3-6 months every year.

That way the "January" kids would sometimes be the oldest in their group, and would sometimes be the youngest. Depending on how they did it, a kid might either spend two seasons in one age group, or skip an age group altogether.

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timbasile t1_iyo7dr9 wrote

BMX just uses your current age to set cohorts. If you're 8 and it's your birthday later this week, you race the 8 year olds since you're still 8.

Next week, you'll be 9, so then you'll race against the other 9 year olds.

There's still an effect - since at least here in Canada the sport shuts down for the winter, so people born late fall would spend the most race days in the cohort as an older athlete, but I'd imagine it's muted vs other sports using a calendar approach.

Though with an individual sport like BMX, it's easier to do this since it doesn't have the same team forming process . You just show up at races and race whoever happens to also show up.

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SolemnLoon t1_iyo8xun wrote

Ahh, that works. And you're right that it's much easier in a solo sport than a team sport. It'd be tough on a coach if every time a kid had a birthday, he moved on to the next team.

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eltos_lightfoot t1_iyo7obi wrote

I always felt he missed talking about the few kids that actually made it from the last months. What made them succeed in spite of being in that cohort? Weren’t they the true outliers?

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marriedacarrot t1_iyobq5b wrote

In India, reporting the wrong birth month to the school is super common (or it used to be), from parents trying to optimize their kids' chance of academic success.

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enny_el t1_iyom36a wrote

That's crazy! I could totally see that happening some places here too though.

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marriedacarrot t1_iyp045e wrote

Come to think of it, I don't remember providing a copy of the birth certificate when I enrolled my kid in kindergarten. I think most American parents are so eager to get their kids out of the house and into free childcare (er, I mean school) that the deception would be more likely to go the other way (pretending your kid is older than they really are).

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enny_el t1_iyp2iix wrote

I was definitely one of those parents desperate to get my kids to school as soon as possible! But one has a September birthday and is the youngest in his year, and I know that other parents, in a different position (I've, who could afford private childcare) held back their kids with September birthdays because of this idea they would be more likely to get college sports scholarships or do better or whatever. Not being from the US and having gone to uni with people from other countries (who start school at different times and ages), i have always thought this is really weird -- like surely, and compared to kids from other nations with different school systems, surely this can't still be giving intentionally-held-back kids an edge once they are older?

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marriedacarrot t1_iyp5hs2 wrote

>surely this can't still be giving intentionally-held-back kids an edge once they are older?

That's the weird thing: It does. Being the oldest/tallest/strongest/smartest kid in your cohort means coaches give you more game time, or you gain more academic confidence and skill among your peers in early grades. And it snowballs from there.

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enny_el t1_iyp5ubm wrote

I just find it hard to believe that that applies universally across countries and cultures and hemispheres and school systems and everything. But maybe I just don't want to believe it because it means I already screwed everything up for my September-born kid! Doomed from birth, poor thing!

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marriedacarrot t1_iyp8q6g wrote

Which month is the "right" month definitely changes by culture, but the premise that being the oldest in your childhood cohort confers an early advantage seems to hold across multiple countries.

If it makes you feel any better, the magnitude of the advantage conferred isn't huge. I'm a September baby, was almost always the youngest in my class, and (at the risk of bragging) I'm objectively successful. I was never great at sports, but being several inches below average is probably the culprit. :)

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zedfrostxnn t1_iyomcwd wrote

So do parents in India want their children to be the oldest in class?

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marriedacarrot t1_iyoztd2 wrote

Yes, according to my co-workers from India. They're pretty upfront about it, too (and pretty upfront about being in arranged marriages).

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marriedacarrot t1_iyp0d30 wrote

In my neck of the woods (California) the cutoff is September 1, but it used to be December 31. You had a lot of kids going halfway through Kindergarten as 4-year-olds. Now those Sept-Dec babies go to "transitional kindergarten" first.

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DesmadreGuy t1_izl8jhl wrote

Some recent studies have shown that holding boys back a year is actually beneficial to their success in school, while starting girls at the usual age is suggested, because girls mature faster than boys. Several friends and relatives who have recently had children are seriously considering holding back their boys and letting the girls go as prescribed by the school district. Based on my own children, this seems entirely on target.

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MRKworkaccount t1_iynb3ht wrote

That would explain the September jump, I would guess that one or more countries also uses June as the cutoff

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Jimboats t1_iyo94m2 wrote

Not in Scotland. The oldest kids in the year are born 1st March, the youngest end of Feb. The September kids are squarely in the middle.

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ImNoAlbertFeinstein t1_iyojxvt wrote

US has september cutoff as well.

August kids are the youngest in the class and September kids are the oldest in the class.

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Lord_Bobbymort t1_iymszxt wrote

Here's the data on hockey. https://www.quanthockey.com/nhl/birth-month-totals/nhl-players-career-stats.html

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TurtleWitch t1_iyn4ibu wrote

It basically gets lower and lower throughout the months

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Top_Election3816 t1_iyodjbc wrote

Why is april so low, its in the middle of spring.

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Lord_Bobbymort t1_iyog0u0 wrote

The theory is that if you're older each year in your youth playing with and against younger players you don't improve skills as much, and if you're younger playing with and against older players you can get better.

There's different cutoffs for different sports at different times of year based on eligibility and when each sport plays in the year, so different birth months have different effects on different sports.

That's my understanding at least, but not particularly answering your question about April.

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aj55raptor t1_iyoj3gp wrote

It's actually the opposite. January and February are the highest above and for hockey, because these kids are usually more physically developed than peers. This leads to being selected for elite camps/teams earlier, which compounds throughout their lives. Another cool economics type phenomenon in soccer (may no longer be true), a study was done early 2000s, there's a perfect balance of wealth of parents on average for professional soccer players in Brazol: enough that their nutrition is never sacrificed, but not enough money for structured programs after school, means they're fit but also non stop playing street soccer.

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Embarrassed-Loss-118 t1_iyvozd1 wrote

It is like that in schools, more grown folks develop better in schools, and if the groups are made based on birth year, people who are born in 1st months are less likely to fail the course than their last months counterpart

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The--Strike t1_iyp0tf1 wrote

As the other person commented, it’s the opposite. At young ages, the difference of 11 months is a huge percentage.

Let’s say we have 2 players we have to choose between. Player A and Player B. Both were born in the same calendar year, so for many sports they are grouped together for divisions and such.

Player A was born in January

Player B in December.

Let’s also imagine that they are 8 years old, trying out for their first travel team. At this point in their lives, 11 months of extra growth has given Player A a slight advantage, and the coach picks him for the team. Player B doesn’t make it, but sticks with the sport in recreational leagues.

Player A however gets more specialized coaching, more practice since they’re also playing rec league and travel, and they get more experience playing at a more “serious” level.

Well now it’s a year later, and time for tryouts again.

Player A still has 11 months of growth over Player B, but he’s also got a year of more intensive, in depth training, and more time playing the sport. Even though Player B has been practicing his best, and playing rec level, he just hasn’t developed at the same rate. Plus, he’s still 11 months behind on his physical growth. This gap in skill, experience, and maturity has prevented him from making the team again.

A year later, their 3rd tryouts, will show the divide between the two players has grown even further than the previous years, and any hope of Player B catching up is looking unlikely without some serious, specialized training.

This cascading effect continues throughout their lives, and the effects can be seen greatly when puberty enters the equation, and the rapid development of some players, but not others, coincides with important milestones, like making a high school sports team, or some other big event.

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joellarson1 t1_iypqvga wrote

Also, an important distinction in this is that those 11 extra months of growth isn't just physical size. It's 11 extra months of using their body and mind in everyday life, gaining coordination, balance, depth perception and all the other physical and mental components that go into being a good athlete.

Player A has had over 10% more time alive for their brain to develop than player B by the time they start playing their sport.

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Zealousideal_Bag6158 t1_iyqir5g wrote

Values ​​that span multiple order quantities. But instead we have a fixed set of values ​​(Jan-Dec) with no positional notation. If we try to convert and apply the months to their numerical values

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rayparkersr t1_iynwxzy wrote

As well as the school cut off from kindergarten.

The youngest kids are more likely to underachieve. Amazing that it's so clearly pronounced though.

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silforik t1_iyqcwyc wrote

I was the youngest in my grade, and I skipped a year. I think it was an advantage to start college at 16 (many start even younger)

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idksonotclever t1_iynj1vk wrote

Malcolm Gladwell wrote about this phenomenon in his book "Outliers"... great read.

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vineyardmike t1_izk59nd wrote

He just covered this again in the Revisionist History podcast. The age effect is definitely a thing.

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vxyg t1_iyp8pwa wrote

Read the book “Outliers”. talks about this exact thing. are you really naturally good at soccer? or were you born at the right time and thus were a step ahead from the get-go

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Embarrassed-Loss-118 t1_iyvopby wrote

That's because in sub 20 or sub 18 etc, when you are more grown you have more advantage, so it's more usual to have the bests (usually more grown, like January February and 1st months of the year) the continue playing till being professional

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