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This is interesting. They seem to think it is in utero effect. Maybe Vitamin D? I wondered if they considered if the cause is age when starting school. I kn

This is interesting. They seem to think it is in utero effect. Maybe Vitamin D? I wondered if they considered if the cause is age when starting school. I know that birth month has pretty powerful effects for educational attainment.

sillysaurus3 12y ago
What month should I conceive my child to maximize their educational attainment? I'm only half joking.
- jcampbell1 12y ago
  Depends on the rules which vary by location, but you want your kid to be the oldest in the class. Your older kid is going to believe she is very bright in 1st grade, and have a lifetime of confidence to achieve great things. The real reason she was such a good student in 1st grade is because she was just older.
  - ekianjo 12y ago
    > The real reason she was such a good student in 1st grade is because she was just older. That may be an intuitive reasoning but not sure it holds true. I have seen numerous times the youngest students performing actually better in class than older ones. Do you have hard data to support this ?
    - jedberg 12y ago
      I have no hard data, but I have 10 years of anecdotal data (my wife was a 4th grade teacher for ten years and saw just about 1000 students over her career). She says the younger kids definitely do worse by all measures in 4th grade, in large part because of their lack of maturity.
      - ekianjo 12y ago
        > in large part because of their lack of maturity. Maybe that depends on the topic you are teaching then ?
  - kevinalexbrown 12y ago
    Yes but how much does this explain? Even being convinced of the significance of the effect, I'd like to know the magnitude, as well as how much the magnitude changes conditioned on success. E.g. do the very successful (however defined) have a higher likelihood of being the oldest in their class?
  - tempestn 12y ago
    I can't cite any off the top of my head, but more recent research has actually directly contradicted this. Being the oldest is definitely a benefit in athletics due to greater size and strength throughout school. And you're right that older kids have an advantage in early grades in academics as well. In later grades though, that advantage disappears, and in fact, reverses. (The hypothesis I've read is that the reversal is due to greater effort being required in early grades by younger children, resulting in better preparedness for later grades, when the innate advantage of slightly greater age becomes less significant.)
    - desdiv 12y ago
      I found two papers that seem to back jcampbell1 up. http://www.mussioassociates.com/PDF_files/June8.pdf http://www.mussioassociates.com/PDF_files/June8.pdf >Results from this study suggest that a substantial number of students will fall behind their peers in meeting reading and numeracy standard and graduating from grade 12, simply because they are the youngest and most immature in their kindergarten class. http://www.hks.harvard.edu/pepg/PDF/events/Munich/PEPG-04-24Strom.pdf http://www.hks.harvard.edu/pepg/PDF/events/Munich/PEPG-04-24... >The paper explores the strict school enrolment rules to estimate the effect of age at school entry on school achievement for 15-16 year old students in Norway using achievement tests in reading from OECD-PISA. Since enrolment date is common and compulsory for all students born in a particular calendar year, it is possible to identify the pure effect of enrolment age holding the length of schooling constant. The results indicate that the youngest children (born in December) face a significant disadvantage in reading compared to their older classmates. Note that the first study track them all the way until age 18, and the second until 15-16.
      - tempestn 12y ago
        Hmm, I found this New Yorker article supporting my statement: http://www.newyorker.com/tech/elements/youngest-kid-smartest-kid http://www.newyorker.com/tech/elements/youngest-kid-smartest... However, it seems to be drawing skewed conclusions from the research it cites. From the article: "When a group of economists followed Norwegian children born between 1962 and 1988, until the youngest turned eighteen, in 2006, they found that, at age eighteen, children who started school a year later had I.Q. scores that were significantly lower than their younger counterparts. Their earnings also suffered: through age thirty, men who started school later earned less." From the abstract of the paper it references [1]: "We find evidence for a small positive effect of starting school younger on IQ scores measured at age 18. In contrast, we find evidence of much larger positive effects of age at test, and these results are very robust. [...] There appears to be a short-run positive effect on earnings of beginning school at a younger age; however, this effect has essentially disappeared by age 30." Not quite as sensationalist as the summary in the article! Students starting school younger had slightly higher test scores at age 18. However, the age when taking the test had a greater effect, so students starting older would still presumably have an advantage in tests taken at graduation (given that they would still be older). Students starting younger earned more, but only slightly and only until age 30. I expect the real conclusion to be drawn is that it's silly to obsess over what age to start your kid in school. Start them when they seem ready, and spend more time focusing on supporting them at home (in their education and otherwise) than worrying about the findings of these studies. [1]: http://www.nber.org/papers/w13969 http://www.nber.org/papers/w13969
  - desdiv 12y ago
    I know this sub-thread started in half-jest, but your response got me thinking: 1. Month of birth directly determines a child's age compared to their classmates. 2. An older child among younger peers performs better academically. 3. Academic aptitude is correlated with income. 4. Income is correlated with longevity. Admittedly, hypothesis #2 is iffy. And the good old "correlation is not causation" adage applies for #3 and #4.
    - saraid216 12y ago
      > And the good old "correlation is not causation" adage applies for #3 and #4. It does, but it's not hard to come up with plausible causes for the correlation to support in those cases. It is probably more accurate to say "Academic aptitutde correlates with job stability which correlates with lower overall stress levels which is part of the definition for better health which correlates with longevity."
    - tomp 12y ago
      You could easily reverse 2. 2. A younger child among older peers needs to work harder to achieve comparable results. 3. Work ethics are correlated with income.
  - ryanwanger 12y ago
    This is particularly true in sports. There is a chapter in Malcom Gladwell's Outliers all about it.
- Smirnoff 12y ago
  Purely speculative but people whom I know to be the most successful in education and career happen to be born between November and January. Age doesn't matter though. Some of them jumped a few years ahead of their classmates so they surely weren't the oldest in their classes. My mother did think that being the oldest helps (or as she would put it: "School and work can wait. Enjoy your childhood while you can"), so my brother and I weren't allowed to go to school until we were 8. We graduated from high school at the age of 19 & 20. Both of us had 4.0 GPA and landed full rides in foreign universities and became the first generation of college educated people in the last 4 generations that we could trace back
  - ryanjshaw 12y ago
    Speaking from experience, being the youngest appears to have no upsides: you're expected to perform as well as people older than you which creates tons of pressure, you're probably physically smaller which can impact confidence/sports/romance, socially you're a year behind, and it only gets worse later - in many countries the legal drinking age (18) aligns with the average age of entering university which means your options for social development at a crucial stage of development are restricted further, etc. By the time you're 30, an extra year saved going to school earlier means nothing, and the price you paid in terms of developing neurotic conditions (e.g. perfectionism) which impact confidence and social skills, is most definitely not worth it. My kids will follow a similar path to the one you outlined, and I will strongly encourage them to take a gap year before considering applying to university.
    - mhurron 12y ago
      You're projecting. My experiences as the youngest, and smallest in the class until the last year of high school, left me with the following experience - No impact, no differences based on being younger and smaller. I would say what you're saying are results of being younger are actually results of your personality traits, and being a year older would have still lead you to having similar experiences at school.
- ggreer 12y ago
  You'll probably enjoy The Biodeterminist's Guide to Parenting[1] by Scott Alexander[2]. It's a good overview of environmental effects on cognition. There's a section on birth month, and the answer is: It's a trade-off. If you're sending your child to public school, August is best. This makes them the oldest in their grade, giving them advantages that compound throughout school. For private school, February/March might be best, as winter babies have slightly higher intelligence and social skills. 1. http://squid314.livejournal.com/346391.html http://squid314.livejournal.com/346391.html 2. You may have heard of him. Scott is a resident psychologist and writer of Slate Star Codex (http://slatestarcodex.com/ http://slatestarcodex.com/).
  - mod 12y ago
    Well I got the shaft. Early August birthday, nearly the youngest in my grade, public school.
- peteretep 12y ago
  > What month should I conceive my child to maximize their > educational attainment? I'm only half joking. I'm married to a primary school teacher. We are very definitely aiming to have babies born September to December. We aren't even slightly joking about that.
  - vertis 12y ago
    After that you just can't move somewhere that doesn't have the same timing on school years (e.g. Australia).
- CHY872 12y ago
  You want them to be born in September or October (or, more generally, a month or two after the school year starts). Probably October, so that there's no chance they're born in August. They'll be more developed than their July birthday brethren at every stage of their education - it's a very easy boost. For example, exams at 16 in the UK (GCSEs) that by and large everyone takes, you'd expect 54% of autumn birthday children to get 5 grades A*-C. You'd expect 48% of the summer birthday children to achieve this. At age 11, the gap is a slightly larger 8 points in terms of percentage of children who meet expectations. This is a nontrivial difference, which makes it a trivial decision. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/182664/DFE-RR017.pdf https://www.gov.uk/government/uploads/system/uploads/attachm...
- jakobegger 12y ago
  If school starts in september, around christmas.
- vidarh 12y ago
  I've mentioned elsewhere that someone did a study in Norway, comparing salary later in life to age when starting school, and found no statistically significant correlation. This was published as part of discussion on reducing the school starting age. Basically there's very little apparent benefit - at the age most kids start school, brain development appears to be the big brake on learning speed.
- darkmethod 12y ago
  My team of five software developers were all born in December. I didn't think anything of it until I saw this post on HN.
wobbleblob 12y ago
I was wondering about that. I read somewhere else about the birth month effect for professional athletes. Kids whose birthday falls just after the season of their sport starts are up to a year older, bigger and stronger than their peers born earlier in the year, which boosts their confidence to the point that fewer of them quit.

sillysaurus3 12y ago

What month should I conceive my child to maximize their educational attainment? I'm only half joking.

jcampbell1 12y ago
Depends on the rules which vary by location, but you want your kid to be the oldest in the class. Your older kid is going to believe she is very bright in 1st grade, and have a lifetime of confidence to achieve great things. The real reason she was such a good student in 1st grade is because she was just older.
- ekianjo 12y ago
  > The real reason she was such a good student in 1st grade is because she was just older. That may be an intuitive reasoning but not sure it holds true. I have seen numerous times the youngest students performing actually better in class than older ones. Do you have hard data to support this ?
  - jedberg 12y ago
    I have no hard data, but I have 10 years of anecdotal data (my wife was a 4th grade teacher for ten years and saw just about 1000 students over her career). She says the younger kids definitely do worse by all measures in 4th grade, in large part because of their lack of maturity.
    - ekianjo 12y ago
      > in large part because of their lack of maturity. Maybe that depends on the topic you are teaching then ?
- kevinalexbrown 12y ago
  Yes but how much does this explain? Even being convinced of the significance of the effect, I'd like to know the magnitude, as well as how much the magnitude changes conditioned on success. E.g. do the very successful (however defined) have a higher likelihood of being the oldest in their class?
- tempestn 12y ago
  I can't cite any off the top of my head, but more recent research has actually directly contradicted this. Being the oldest is definitely a benefit in athletics due to greater size and strength throughout school. And you're right that older kids have an advantage in early grades in academics as well. In later grades though, that advantage disappears, and in fact, reverses. (The hypothesis I've read is that the reversal is due to greater effort being required in early grades by younger children, resulting in better preparedness for later grades, when the innate advantage of slightly greater age becomes less significant.)
  - desdiv 12y ago
    I found two papers that seem to back jcampbell1 up. http://www.mussioassociates.com/PDF_files/June8.pdf http://www.mussioassociates.com/PDF_files/June8.pdf >Results from this study suggest that a substantial number of students will fall behind their peers in meeting reading and numeracy standard and graduating from grade 12, simply because they are the youngest and most immature in their kindergarten class. http://www.hks.harvard.edu/pepg/PDF/events/Munich/PEPG-04-24Strom.pdf http://www.hks.harvard.edu/pepg/PDF/events/Munich/PEPG-04-24... >The paper explores the strict school enrolment rules to estimate the effect of age at school entry on school achievement for 15-16 year old students in Norway using achievement tests in reading from OECD-PISA. Since enrolment date is common and compulsory for all students born in a particular calendar year, it is possible to identify the pure effect of enrolment age holding the length of schooling constant. The results indicate that the youngest children (born in December) face a significant disadvantage in reading compared to their older classmates. Note that the first study track them all the way until age 18, and the second until 15-16.
    - tempestn 12y ago
      Hmm, I found this New Yorker article supporting my statement: http://www.newyorker.com/tech/elements/youngest-kid-smartest-kid http://www.newyorker.com/tech/elements/youngest-kid-smartest... However, it seems to be drawing skewed conclusions from the research it cites. From the article: "When a group of economists followed Norwegian children born between 1962 and 1988, until the youngest turned eighteen, in 2006, they found that, at age eighteen, children who started school a year later had I.Q. scores that were significantly lower than their younger counterparts. Their earnings also suffered: through age thirty, men who started school later earned less." From the abstract of the paper it references [1]: "We find evidence for a small positive effect of starting school younger on IQ scores measured at age 18. In contrast, we find evidence of much larger positive effects of age at test, and these results are very robust. [...] There appears to be a short-run positive effect on earnings of beginning school at a younger age; however, this effect has essentially disappeared by age 30." Not quite as sensationalist as the summary in the article! Students starting school younger had slightly higher test scores at age 18. However, the age when taking the test had a greater effect, so students starting older would still presumably have an advantage in tests taken at graduation (given that they would still be older). Students starting younger earned more, but only slightly and only until age 30. I expect the real conclusion to be drawn is that it's silly to obsess over what age to start your kid in school. Start them when they seem ready, and spend more time focusing on supporting them at home (in their education and otherwise) than worrying about the findings of these studies. [1]: http://www.nber.org/papers/w13969 http://www.nber.org/papers/w13969
- desdiv 12y ago
  I know this sub-thread started in half-jest, but your response got me thinking: 1. Month of birth directly determines a child's age compared to their classmates. 2. An older child among younger peers performs better academically. 3. Academic aptitude is correlated with income. 4. Income is correlated with longevity. Admittedly, hypothesis #2 is iffy. And the good old "correlation is not causation" adage applies for #3 and #4.
  - saraid216 12y ago
    > And the good old "correlation is not causation" adage applies for #3 and #4. It does, but it's not hard to come up with plausible causes for the correlation to support in those cases. It is probably more accurate to say "Academic aptitutde correlates with job stability which correlates with lower overall stress levels which is part of the definition for better health which correlates with longevity."
  - tomp 12y ago
    You could easily reverse 2. 2. A younger child among older peers needs to work harder to achieve comparable results. 3. Work ethics are correlated with income.
- ryanwanger 12y ago
  This is particularly true in sports. There is a chapter in Malcom Gladwell's Outliers all about it.
Smirnoff 12y ago
Purely speculative but people whom I know to be the most successful in education and career happen to be born between November and January. Age doesn't matter though. Some of them jumped a few years ahead of their classmates so they surely weren't the oldest in their classes. My mother did think that being the oldest helps (or as she would put it: "School and work can wait. Enjoy your childhood while you can"), so my brother and I weren't allowed to go to school until we were 8. We graduated from high school at the age of 19 & 20. Both of us had 4.0 GPA and landed full rides in foreign universities and became the first generation of college educated people in the last 4 generations that we could trace back
- ryanjshaw 12y ago
  Speaking from experience, being the youngest appears to have no upsides: you're expected to perform as well as people older than you which creates tons of pressure, you're probably physically smaller which can impact confidence/sports/romance, socially you're a year behind, and it only gets worse later - in many countries the legal drinking age (18) aligns with the average age of entering university which means your options for social development at a crucial stage of development are restricted further, etc. By the time you're 30, an extra year saved going to school earlier means nothing, and the price you paid in terms of developing neurotic conditions (e.g. perfectionism) which impact confidence and social skills, is most definitely not worth it. My kids will follow a similar path to the one you outlined, and I will strongly encourage them to take a gap year before considering applying to university.
  - mhurron 12y ago
    You're projecting. My experiences as the youngest, and smallest in the class until the last year of high school, left me with the following experience - No impact, no differences based on being younger and smaller. I would say what you're saying are results of being younger are actually results of your personality traits, and being a year older would have still lead you to having similar experiences at school.
ggreer 12y ago
You'll probably enjoy The Biodeterminist's Guide to Parenting[1] by Scott Alexander[2]. It's a good overview of environmental effects on cognition. There's a section on birth month, and the answer is: It's a trade-off. If you're sending your child to public school, August is best. This makes them the oldest in their grade, giving them advantages that compound throughout school. For private school, February/March might be best, as winter babies have slightly higher intelligence and social skills. 1. http://squid314.livejournal.com/346391.html http://squid314.livejournal.com/346391.html 2. You may have heard of him. Scott is a resident psychologist and writer of Slate Star Codex (http://slatestarcodex.com/ http://slatestarcodex.com/).
- mod 12y ago
  Well I got the shaft. Early August birthday, nearly the youngest in my grade, public school.
peteretep 12y ago
> What month should I conceive my child to maximize their > educational attainment? I'm only half joking. I'm married to a primary school teacher. We are very definitely aiming to have babies born September to December. We aren't even slightly joking about that.
- vertis 12y ago
  After that you just can't move somewhere that doesn't have the same timing on school years (e.g. Australia).
CHY872 12y ago
You want them to be born in September or October (or, more generally, a month or two after the school year starts). Probably October, so that there's no chance they're born in August. They'll be more developed than their July birthday brethren at every stage of their education - it's a very easy boost. For example, exams at 16 in the UK (GCSEs) that by and large everyone takes, you'd expect 54% of autumn birthday children to get 5 grades A*-C. You'd expect 48% of the summer birthday children to achieve this. At age 11, the gap is a slightly larger 8 points in terms of percentage of children who meet expectations. This is a nontrivial difference, which makes it a trivial decision. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/182664/DFE-RR017.pdf https://www.gov.uk/government/uploads/system/uploads/attachm...
jakobegger 12y ago
If school starts in september, around christmas.
vidarh 12y ago
I've mentioned elsewhere that someone did a study in Norway, comparing salary later in life to age when starting school, and found no statistically significant correlation. This was published as part of discussion on reducing the school starting age. Basically there's very little apparent benefit - at the age most kids start school, brain development appears to be the big brake on learning speed.
darkmethod 12y ago
My team of five software developers were all born in December. I didn't think anything of it until I saw this post on HN.

wobbleblob 12y ago

I was wondering about that. I read somewhere else about the birth month effect for professional athletes. Kids whose birthday falls just after the season of their sport starts are up to a year older, bigger and stronger than their peers born earlier in the year, which boosts their confidence to the point that fewer of them quit.