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Lifespan depends on month of birth (2000)

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Re: Lifespan depends on month of birth (2000)

#11

Post by ryanwanger »

jcampbell1 wrote: post #5
sillysaurus3 wrote: post #4

Earlier quoted context omitted.

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

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.

This is particularly true in sports. There is a chapter in Malcom Gladwell's Outliers all about it.

Re: Lifespan depends on month of birth (2000)

#13

Post by desdiv »

tempestn wrote: post #6
jcampbell1 wrote: post #5

Earlier quoted context omitted.

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.

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 revers…

I found two papers that seem to back jcampbell1 up.

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-04-24...

>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.

Re: Lifespan depends on month of birth (2000)

#14

Post by joe_the_user »

The correlation is in terms of fractions of a year so they add up to an average of plus-or-minus a few month over a lifetime. The three curves don't seem to have a very close relationship to each other though there are some similarities.

I assume that if they are getting a meaningful correlation, it is over a large amount of data. It seems logical that at large scale, date born would correlate with a variety of things in various areas - social class and wealth come to mind.

I think it's a matter of taste whether one says "wow, throw enough data together you find unexpected correlations" or "garbage in, garbage out". A life insurance company could eek out a bit of profit changing its price structure on this data - if it didn't have far more to lose if the use of such tactics became public.

I bet someone can use this to claim astrology has validity too.

Re: Lifespan depends on month of birth (2000)

#15

Post by vlasev »

ekianjo wrote: post #8
reasonattlm wrote: post #2

Leonid Gavrilov and Natalia Gavrilova are a good resource for this sort of demography and epidemiology of aging. [1] In particular they have a lot of material on season of birth effects. [2] Tangentially related to the seasonal effects is data suggesting that solar cycles also influence longevity, possibly through quite indirect responses to levels of UV exposure in pregnant women. [3] You can see how this might be r…

But the data in the post does not seem to be super correlated to seasons. You can see that the decrease in life expectancy occurs way before spring (as soon as February) which is still supposed to be a winter month. So the season link is weak.

I'm thinking it has to do with the continuous day/night cycle. It'll be interesting to see if there are any changes with latitude, in particular, what happens in countries closer to the equator.

Re: Lifespan depends on month of birth (2000)

#16

Post by tempestn »

desdiv wrote: post #13
tempestn wrote: post #6

Earlier quoted context omitted.

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 revers…

I found two papers that seem to back jcampbell1 up. 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-04-24.…

Hmm, I found this New Yorker article supporting my statement: 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

Re: Lifespan depends on month of birth (2000)

#17

Post by jedberg »

ekianjo wrote: post #9
jcampbell1 wrote: post #5

Earlier quoted context omitted.

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.

> 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 ?

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.

Re: Lifespan depends on month of birth (2000)

#19

Post by Smirnoff »

sillysaurus3 wrote: post #4
jcampbell1 wrote: post #3

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.

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

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

Re: Lifespan depends on month of birth (2000)

#20

Post by jrapdx3 »

reasonattlm wrote: post #2

Leonid Gavrilov and Natalia Gavrilova are a good resource for this sort of demography and epidemiology of aging. [1] In particular they have a lot of material on season of birth effects. [2] Tangentially related to the seasonal effects is data suggesting that solar cycles also influence longevity, possibly through quite indirect responses to levels of UV exposure in pregnant women. [3] You can see how this might be r…

The differential exposure to UVB, that is, sunlight, was the first thing I thought of reading this article. It is especially likely among people born in the industrial-era 19th century, at a time before the nature of the link between health and sunlight was clearly identified.

Around a hundred years ago, the role of UV in preventing rickets was confirmed. By the 1930's, vitamin D supplementation of foods became widespread, and the most obvious manifestations of deficiency (e.g., rickets) essentially disappeared. Studied intensively since the 1930's numerous effects of D (or lack of it) have been reported, and recently interest has exploded.

Increasingly evidence implicates low vitamin D levels in a wide range of conditions, such as autoimmune disorders, cancer, and metabolic disease, that are likely contributors to reduction of life expectancy.

Seasonality of vitamin D level is well known. In northern latitudes (>=45th parallel) the nadir occurs around March-April, and the peak is measured on average in September-October. The timing of these fluctuations appears quite congruent with the article's assertions about life expectancy, so it's reasonable to think there is a connection.

For anyone interested in vitamin D, I highly recommend this excellent review: http://www.tandfonline.com/doi/full/10.4161/derm.24494

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