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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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desfirsit OP t1_iym82xu wrote

The relative age effect is documented in a wide range of sports and also in academics. A child born in January will be 11 months older than a child born in December the same calendar year, which is a big relative difference at young ages. If coaches don't think of this, they will misperceive the older kid as being more mature and talented, and will then encourage the older kid more.

I took data on all players in the FIFA World Cup and checked their birth month. Just as expected, the most common months to be born are January, February and March.

Some countries may have other cutoff dates for starting school or sports teams than January 1, but despite this, the effect shines through.

Made in R using the ggplot2 package. Data from fbref.com.

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diamond280779 t1_iymf8t6 wrote

For academics September is the relative age effect start point. Most sports in Northern Europe work the same way Football 100% does so here in the UK

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desfirsit OP t1_iymiz5r wrote

It depends on the country. In Sweden where I live January is the cutoff for both schools and most sports.

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diamond280779 t1_iymm4uo wrote

England, Wales, Belgium, France, Germany, Croatia, Netherlands, Poland, Portugal, Serbia, Spain and Switzerland all start in September (academics)

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hoffmistrz t1_iymr41b wrote

Well, academic year in Poland starts in september but you still go to classes according with year you were born in. Children from January wil be the oldest in class and the ones from December the youngest(There are also cases where a children from example December can be moved to another year)

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locky_ t1_iymtfi7 wrote

That is not correct, at least in Spain. The classes start on September, but the students go to class following the calendar year. Someone born in April and someone born in November of the same year will go to the same class. And the same for sports.

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Junkley t1_iyn6jh7 wrote

Much of the US goes by the Sept cutoff too. There are some places that use raw age for sports but most use school class and the cutoff varies but usually is around Sept 1st or Labor Day

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FartingBob t1_iyo6jzr wrote

As a Brit, my first thought was "wow that's a weird way of doing it" then my second thought was "Hang on, no it isnt. Its the only logical way of doing it. Why the fuck do we still start a new school year in September???".

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desfirsit OP t1_iyo7dtj wrote

Well we start the new school year in august, but the cut-off is still January! Everybody that is born a specific calendar year starts school the same time in August. If you are born December 31 the year before you start in August a year earlier.

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FartingBob t1_iyo7j2u wrote

Oh, well then my first thought was correct. Your way is weird! At least out cutoff is start of september as well.

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FITnLIT7 t1_iymced5 wrote

My fiancee really doesn’t understand why I want to plan to have our child earlier in the year. I seen the effects first hand playing competitive sports at a young age.

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ranseaside t1_iyo4lnx wrote

My friends planned this, they planned to have a baby in January for the same reason. They ended up with a premature baby’s who was born in December.

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FITnLIT7 t1_iyo511b wrote

I mean it can happen. I wouldn’t necessarily aim for a child to be born in January for this reason. My son now was born in April. And If I could “aim” for a date it would be Feb/March. People can deny it all they want but I’ve seen too many late year baby boys get bullied for being smaller - even if it’s just In the early years of school that shit leaves a lasting negative affect.

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ranseaside t1_iyo5l0u wrote

No shade from me. I won’t fault any parents for wanting the best for their child. I had fertility issues so I am just happy I had a kid whenever it happened, I couldn’t plan it like that. Tho I have also seen many kids born later on the h the year who were big and strong (I am a teacher), so many factors go into how a child becomes (genetics, diet)

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FITnLIT7 t1_iyo7lm3 wrote

Glad that worked out for you, being a parent is a wonderful thing. (My first is 7 months old). Genetics will always play a major part but that I can’t control (not some gene editing nut job) but if you have genetics as a December baby to outgrow and outperform everyone else your age, just imagine that same kid as a January baby. It’s really just a preference thing and it’s a small thing I can control to help tip the odds in my child’s favour in this difficult world.

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Easter_1916 t1_iyow7x6 wrote

Or you could do what they do in the southern USA and have them early in year AND hold them back a year. I started college at 17 and my roommate turned 20 freshman year.

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Anachronism-- t1_iynl85m wrote

Malcom gladwell did an update on his podcast and observed that many parents are using his data as a reason to hold their children back a year to give than an academic advantage.

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abzlute t1_iyo6xu6 wrote

Idk which specific sport you're concerned with and if it would be done through school or separately, but if we're going with school grade cutoffs then why not just let the dice fall and if they are near the cutoff then keep them home for an extra year? They would be the oldest in their grade, but only by the same margin that the the otherwise oldest kids are/would be.

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FITnLIT7 t1_iyo77h6 wrote

Sports here (Canada) don't go by school grade... they go by birth year. Sports aside, I would rather not have a December 2024 baby in classes with 2025 kids. I'd rather my kid be a Jan-March 2025 kid.

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abzlute t1_iypq5k8 wrote

Is birth year more culturally significant in schools there? Here it's not really even a consideration. Ofc the school starting cutoff is usually based on age at the start of the school year in august iirc, not on calendar year, so I had a mix of classmates born in 94 and 95 for instance. Being born in summer made me one of the youngest, and being born in december would place someone in the older half. We only really associated with grade level, and with graduation year (both high school and college). And assuming your sports are through the school system (most are, but not all, and those that aren't are usually more chill) I don't think actual age affects eligibility at all until it's like state and national championship level U16, U18, U23, etc categories.

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Analyst214 t1_iymhmz4 wrote

Well good news is if you are perusing Reddit and not busy doing something else then your child most likely won’t advance far into competitive sports so feel free to have it whenever

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FITnLIT7 t1_iymhsqi wrote

So you just woke up and chose violence? Perhaps one of the most useless comments I have ever read, thanks for the invaluable input.

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Analyst214 t1_iymi9a8 wrote

It is what it is the truth hurts us all my friend

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FITnLIT7 t1_iymj7vu wrote

Having a semi-professional sport background and a cushy desk job that allows me to surf the web definitely indicates a child that will be unable to perform well in sports you are right.

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Analyst214 t1_iymm0gz wrote

And that’s why your child won’t make it far, most athletes are dictated by genetics and discipline. If we go by chance and your Reddit history we can assume your offspring won’t make it far

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fongletto t1_iyn1yfv wrote

Or it could be because they're generally the biggest, smartest and most mature of their peer group they develop better confidence and leadership skills and are therefore more likely to pursue things to their highest level.

Or maybe a little from both.

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Boris_Ignatievich t1_iym8d5e wrote

I assume that September spike is the places in eg Europe that group on school year for youth games?

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fix-ur-acrostics t1_iymw7sb wrote

It's probably just the fact that September is the most common birth month

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Top_Election3816 t1_iyodp6h wrote

September is 9 months from december… They fuck a lot on the holidays

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Josquius t1_iyo8u3k wrote

Yes. Big historic issue in England that your chances of being scouted are much higher if you're born in the second half of the year so are the biggest in your age group.

These days scouts actively seek to look beyond this. Trying to look at fundamental ability rather than heavily physique related performance.

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desfirsit OP t1_iym8hpb wrote

Can be! Or randomness.

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11160704 t1_iymar67 wrote

September also is a months in which many births occur in Europe because 9 month earlier is December when people spend much time with their partners and indoor activities are more popular than outdoor activities.

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CarefulCoderX t1_iyniach wrote

9 months before September is December, most people take a lot of December off because of the holidays. It's also the end of the year when people reflect on their lives and what they may want to do next so I think it makes sense that a lot of people try for a baby around this time of year.

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SMS_Scharnhorst t1_iyopeep wrote

except in Germany for example we don't group football teams the same way we do with the school year. for football it is an entire year from Jan to Dec, for school it is from July 1st to June 30th

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Boris_Ignatievich t1_iyp5137 wrote

I don't mean that everywhere in Europe does it, but quite a few places do, some of which are in europe (eg the UK)

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creektrout22 t1_iymuyib wrote

Interesting data, but shouldn’t this also be compared to the average birth month pattern in general? That would provide more evidence for the relative age effect. Births are not equal across all months to start with in humans (even simplistically based on days of the moths).

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marbel29 t1_iynmh8j wrote

As a economist, was going to say that. This is partly inconclusive data. It’s need to be crossed like you said with average births per month maybe across healthy males between 8-18 years of age and 18-35, to differentiate if this affects only in youth or in adulthood as well

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RJrules64 t1_iyn02iq wrote

This is true and I suspect that would explain the spike in September!

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dcolomer10 t1_iynasoz wrote

The September one can be explained because some countries have a September cutoff for academics/sports instead of January. At least, from my experience, UK and US have a September cutoff. In Spain, France, Italy Im sure the cutoff is in January, I’m not sure about the rest.

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orlevko t1_iyntfjz wrote

And also, error bars and statistical significance tests would be useful here

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Totale-Substanz t1_iym8gp6 wrote

I was born in March and am still shitty at everything.

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furomaar t1_iymje3p wrote

I was born in the beginning of february and my parents sent me to school a year early. Good job parents.

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shamdamdoodly t1_iypyt1p wrote

This is looking at a single variable accounting for nothing. Basically a small linear correlation in a small sample size. Wouldn’t look into it too much

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Dank_e_donkey t1_iyq7571 wrote

Same birthday as Neymar Jr and CR7, but I can't even dribble the ball.

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meinaustin t1_iymzmvv wrote

This was covered by Malcolm Gladwell in Outliers, except for hockey.

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CRD_Visual_Arts t1_iynfy8n wrote

Yes, great book. I thought he covered hockey as well.

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MKerrsive t1_iynryk5 wrote

I think he means "Gladwell discussed this phenomenon, except the sport was hockey instead of soccer." Outliers specifically discussed Canadian youth hockey.

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DammitAnthony t1_iymlpig wrote

This should not be done by calendar month but rather relative to school year start depending on their country. A September child in a September school year is relatively the same age as a January child in a January school year.

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pinkshirtbadman t1_iymo0ok wrote

It depends too much on the organization to really be able to split it up for every case.

In the US age /birthday cutoffs vary place to place, but Aug-sept is most common for school classes meaning you are right a child born in September is 10-11 months older than some of their peers in the same class which can be a significant advantage particularly in early years.

Kids' sports (and also many other non sport related extra-circular activities not directly sanctioned by the school) tend to be broken down either by grade, in which case the ~Fall-Late Summer range is most relevant, or by age regardless of grade, in which case Jan-Dec will be the range that matters.

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DammitAnthony t1_iympt7r wrote

Interesting article breaking down just North American sport leagues.

https://www.researchgate.net/publication/290649143_Does_Relative_Age_Affect_Career_Length_in_North_American_Professional_Sports/download

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pinkshirtbadman t1_iymqxfw wrote

It's interesting, and it kind of works to break it down this way. I didn't fully articulate what my concern is in my other comment, my question is how do you account for situations in which the same person in the same activity would be on opposite ends of the age gap depending on where they play.

A child born late in the year would have the most advantage in school sports, even say just PE class all the way up to the varsity team in high school, but that same individual (particularly as a younger child) would be on the bottom end of the age gap advantage in a city sponsored league that uses the calendar year

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Jumpshot1370 t1_iyoh5od wrote

In America, at least in my school system in California, the cutoff is in November. So a person born December 2003 - November 2004 would have graduated high school in 2022, someone born December 2004 - November 2005 will graduate high school in 2023, etc. There are some exceptions on the older side, children who started school a little bit late.

At my high school, which I graduated from in 2022, there is a student who was born in October 2005 and is currently a junior. Another student born in November 2005 is currently a senior. There are a few similar cases in other classes.

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[deleted] t1_iymglri wrote

My twin brother and I repeated 1st grade and I always wonder if that was responsible for our academic success. Always being a year older is a huge advantage when you're a kid. Definitely helped in sports too because I hit puberty a grade early and was like 6in taller than my peers in middle school.

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No-Statistician7510 t1_iyogd6z wrote

We figured out on my high school varsity team that ~60% of the team was born between September and November. We then realized that because of the cut off for the grade being September, those born in the early months of the school year then got to play with the older kids who were a grade level above them, making them better players.

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corrado33 t1_iyniwjv wrote

This just backs up what I've been saying for YEARS about children's sports.

It has NOTHING to do with talent, and EVERYTHING to do with maturity.

Your kid isn't "good" at sports, they're just bigger than most people they're playing against.

If you mature early (like I did), you will likely be "good" at sports. (I was 5'10" in 8th grade.) You will be pushed to do sports more than someone who matures later, so, by the time that talent DOES come into play, you have many many more hours of training than someone who didn't start playing until a few years later.

It's relatively rare that someone matures late or is small and their talent alone carries them to the furthest levels of sports. (Think of people who were the "wrong" size for their sport. Generally someone who is very small in most american sports.)

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-Twigs- t1_iyqia5y wrote

I don't really think it'd be correct to say it's 100% a question of maturity and nothing else. Things like genes, nutrition and health are examples of factors that could be playing a part. Loads of things contribute to a child even getting the chance to start playing a sport, which is a requirement for them to be good at it. To reduce all that down to differences in "maturity" is a bit simplistic in my mind.

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corrado33 t1_iyrm080 wrote

Of course you are correct. I'm just saying that the MAIN factor in determining if someone will be good at sports is literally how physically mature/how big they are. (As a kid, "size" is pretty much determined by physical maturity (and to a lesser extent, the things you mentioned).

Some dirt poor, poorly fed kid who is 5'6" (due to maturing quilckly) is still going to destroy a rich, well fed kid who is 4'10" tall in any physical sport.

Genetics and what not will determine the final height of most people, but the speed at which one matures will determine how quickly they get there (and therefore, how much larger they are than their peers when they are young.)

And let's be honest here, MOST children who will be playing sports (in the US) are fed well enough not to affect development.

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paulbieniek t1_iyowvsq wrote

The book "Outliers" by Malcolm Gladwell dives into this phenomenon. Great read.

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Kriskao t1_iymjodr wrote

This would make sense in the Southern Hemisphere where school is February to December, but makes less sense in most of the world, where school begins in August or September.

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scandinavianleather t1_iymv8j0 wrote

Doesn't matter when schools starts, it matters where the age cutoff is. I live in Canada where school starts in September, but you are divided by birth year. Is that not the norm in the Western World?

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InterMando5555 t1_iymxfz6 wrote

In the US (well at least my school district in Minneapolis) it oriented around a school calendar i.e. those born September 2000 to August 2001 were all in the same class. People born in September and October were always the oldest in their class. Long story short this graph and the interpretation of this graph is wrong for a number of geographical and cultural inconsistencies.

2

Dontknowhowtolife t1_iyoar9z wrote

I live in Argentina where school year is March- December and you're divided from July (born in year n) to June (born in year n+1)

1

dcolomer10 t1_iynb4ju wrote

It’s the cutoff, not when it starts. In most European countries such as my own, you play with people from your age group, which is your calendar year. So, people born in January are playing with people born in December, nearly a year younger. This is especially beneficial for physical sports where a year difference can be very influential.

3

bradles0 t1_iynczd6 wrote

There are two cutoff points, one in September at the beginning of the school year, and one in January at the beginning of the calendar year.

Oh hey guess where the two spikes are...

1

Confusion-Neat t1_iymnr95 wrote

Many people are suggesting you should take into account the country of the player, but I'd say to take into account the BIRTH country of the player. Many players are "imported" from other countries.

1

Hello_iam_Kian t1_iyn6wel wrote

My countries national football federation (KNVB🇳🇱) did a study about this and it was in fact right. Many younger players good players will never make it to the professional stage because they are physically underdeveloped in the junior categories.

Sadly, most professional clubs focus on prestation instead of potential.

1

doitnow10 t1_iyn8xro wrote

Same can be observed in all major European pro leagues

1

dba1990 t1_iyn98ly wrote

The parents did coitus in the preceding April, May and June, or the parents eloped to prepare for the World Cup in June/July and then stopped once competition began.

1

excessCeramic t1_iynhf9d wrote

Need to normalize by total number of people born in each month, I assume it’s not uniform

1

Same-Till5174 t1_iynmnfr wrote

Divide the data by hemisphere. It would be really interesting.

1

SW1981 t1_iyntf8d wrote

Probably need to separate them into northern and southern hemisphere players

1

_iam_that_iam_ t1_iynuhh4 wrote

I feel like the kind of parents who plan January births so their kids can have some tiny advantage against their classmates are the kind of helicopter parents that are going to push their kids at every stage and the kids may wind up more successful and in therapy.

1

AdDisastrous6356 t1_iynvv1f wrote

Outliers by Malcolm gladwell has a good explanation for this

1

WhoGotYouSmiling t1_iynvwaq wrote

The book "Outliers" explains exactly why this phenomenon happens.

1

Derped_my_pants t1_iyo0uqi wrote

Would be even better if could be corrected for relative worldwide birth rates per month. For example, September appears to spike, but I recall births being higher in the northern hemisphere in September

1

Josquius t1_iyo8h9a wrote

This is a big known issue in football. They've been working to remedy it in England this century as previously the overwhelming majority of players in the premiership were born in the second half the year, that meaning they were oldest in their school year.

I know several countries have the normal year for their school year cut offs which could be shown here.

1

bezelbubba t1_iyo937q wrote

This and the 10,000 hour rule which is a result of this is one of the main thesis of Gladwell’s Outliers.

1

CurrentDismal9115 t1_iyobadw wrote

Trying to use some psuedo-scientific garbage to prove that this isn't the Age of Aquarius amd we don't run the world! Fer shame!

1

iceytomatoes t1_iyoopbx wrote

i thought there was a bigger divide actually, this looks less extreme than i would expect, are different countries perhaps using different date cutoffs? i'd want to see it by country for that reason

someone posted hockey stats and i thought i'd seen them in the past and saw a more extreme divide as well, it's a lot less than i remember

1

EscapedCapybara t1_iyowcz5 wrote

It also doesn't help if you're late going into puberty. I'm a November and never hit puberty until late in my 14th year. I was smaller in the first part of 10th grade than some of the kids entering 8th grade. It's hard to gain any skills in sports if you're never played because of your size.

1

Raioc2436 t1_iyp5afy wrote

Wouldn’t the age effect be different for countries where the school year starts in Jan-Feb instead of September?

1

rye_domaine t1_iyp7juy wrote

Oh boy another thing to strengthen my imposter syndrome

1

keisagu t1_iypl21w wrote

What about countries in the southern hemisphere, where the school year starts in march?

1

lnieder t1_izjw81g wrote

This is nothing new if you've read Malcolm Gladwell's book Outliers.

1

desfirsit OP t1_izl8hrz wrote

I have, but as you know he did not include data on the 2022 World Cup

1

Individual_Divide333 t1_iymleaf wrote

Benford’s Law

I immediately thought of Benford’s law Considering the months as their numbers 1, 2, 3..

“A logarithmic scale bar. Picking a random x position uniformly on this number line, roughly 30% of the time the first digit of the number will be 1. A set of numbers is said to satisfy Benford's law if the leading digit d (d ∈ {1, ..., 9}) occurs with probability[10]”

A really cool episode of Connected: The Hidden Science of Everything on Netflix, explains the law really well, and has IRS help explain (elusively) how it’s used to detect fraud in real life.

0

Frog23 t1_iymns43 wrote

Benford's law doesn't apply here. It is (best) for numerical values that is spanning multiple orders of magnitude. But instead we have a fixed set of values (Jan-Dec) with no positional notation. If we were to convert the month to their numerical values and try to apply Benford' law, we would need to group the numbers for January, October, November and December to the groups of values starting with 1. That would be a bit more "benfordy", but really overshoot in other direction.

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Individual_Divide333 t1_iympr1x wrote

Ahhhhh totally makes sense. Thank you for deepening my understanding of this cool phenomenon.

2

jaredsolo t1_iyne5w0 wrote

Nope, that's all joke.

Kids born at the beginning of the year used to be bigger than ones from the end of the year, and that's why have better chances to make a professional career, as teams need bigger players, rather than extremely talented ones.

0

IusedtoloveStarWars t1_iypxepe wrote

The month doesn’t matter lol. It’s the phase the moon is in obviously.

All the best players were born on a blood moon when Saturn and Uranus were lined up(common knowledge).

0

LANDVOGT-_ t1_iyne8u5 wrote

This sounds like bullshit. Where on earth is age measured in the birth year instead of the birth day?

−1

The--Strike t1_iyp1gf9 wrote

Sports organizations that want to categorize which age divisions players play in. They don’t care about what day, they want your birth year, and to group you with other kids of the same year.

2

FITnLIT7 t1_iymc091 wrote

Thank god something I can show my fiancée. She really doesn’t understand it. I by no means need to have my next child in January but I just won’t plan to have a late year baby.. for girls it’s not much of an issue, but it makes a difference for boys early in life and sports.

−5

macklamar t1_iyn9vv4 wrote

Since the outcome of the relative age effect is largely due to ,perceived’ talent when compared to peers and therefore better support, you could technically overcome the relative age dilemma by simply encouraging your kid regardless of what month they were born in :)

2

bradles0 t1_iyncqas wrote

But it's about coaches and teachers, not the parents.

1