
Study finds connections between birth month and health - adamsi
http://newsroom.cumc.columbia.edu/blog/2015/06/08/data-scientists-find-connections-between-birth-month-and-health/
======
AndrewOMartin
The linked article's title says "connection", the article says "correlation".

A phrase later in the articles shows that further study _may_ find a
connection; implying that they don't have one already.

A more accurate HN link title is "Study could help scientists uncover new
disease risk factors pertaining to birth date".

~~~
judemelancon
I am unaware of an applicable technical meaning of "connection". Does
"connection" mean "causation" to you in a statistical context? If not, does it
mean something stronger, weaker, or simply distinct? Is there a particular
source for this meaning, like a style guide or technical work? (These are all
honest questions; I like precision as much as the next scientific paper
reader.)

~~~
AndrewOMartin
I expect a usage of the word that means they had a evidence for a certain
amount of the causation.

It's a complicated universe so full causal explanations are pretty much always
unattainable in the real world, but I'd hope for some identification and
discussion of a mechanism.

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islon
"The risk related to birth month is relatively minor when compared to more
influential variables like diet and exercise."

The most important information in the article.

~~~
terminalcommand
Well, some diseases can't be influenced by variables. I have type 1 diabetes
since I was 10 years old and it was caused by sheer luck. As for the study I
was born in November. And I think you could categorize type 1 diabetes as a
viral infection. For me it is accurate.

~~~
matthewmacleod
Well, that's not really true. Type 1 diabetes isn't caused by 'sheer luck' –
there are a whole bunch of known and suspected genetic and environmental
factors. The same applies to other conditions, and I'm not sure 'luck' is much
of a contributor either way.

~~~
terminalcommand
When I got first diagnosed they told me it was due to environmental factors,
but they didn't know for sure. No one in my family had have type 1, so I ruled
out the genetic factor. I know that if I had a child, he/she would have a
higher risk of being sick. I am not an expert on the subject, but it seems
like bad luck for me. I couldn't help not getting the disease. Type 1 has been
around forever. In Ancient Egypt they defined it as the body eating itself.
When I got sick, no one including the doctor suspected that a child could have
diabetes. they had me tested for a lot of things, suspected that I had
tuberculosis. These are my experiences anyway.

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matthewmacleod
I'm surprised there's so much skepticism about this – it seems like an
intuitively obvious result. The date on which a child is born will influence
the environment in which they spend the early months of their lives – levels
of sunlight exposure, temperature, allergens, pesticides and so on, both for
the child and the mother. Given that, and knowledge that exposure to certain
environments and chemicals can change the risk of health conditions later in
life, it's hardly a big leap to demonstrate that correlation through a larger
population-scale study.

I'd be far more surprised if there were _no_ link!

~~~
vlasev
It says 55 conditions are correlated with the month, out of 1688. That's a
rather small effect. The skepticism is well-warranted IMO. Also 39 of them
have been shown to exist before this study so this is not strictly new
knowledge either.

~~~
matthewmacleod
I don't quite understand your point – the number of conditions that are
correlated isn't related to the effect size, is it?

I know it's not new knowledge – that's kind of why I'm unsure about the
skepticism. We know that these effects already exists, and this is a wider-
scale analysis of potential instances of those effects.

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jdmoreira
They assume it's an environmental factor but I wouldn't be so sure.

It's certainly possible that this bias is more related to parents behaviour.
Some parents would conceive in August resulting in their children being born
in May.... Other parents would conceive in January resulting in children being
born in October. People which conceive during different seasons might be
different both genetically and behaviourally which could influence offspring's
health by means of genetic factors but also habits learned from their parents
during childhood (dietary choices for example).

Or not.

~~~
vlasev
Some of the correlations are based on environmental factors that change with
the seasons, i.e. light, temperature, etc.

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droithomme
Astrology makes claims that factors of life are correlated with birth month.
This is a reasonable hypothesis to explore through studies. It is certainly
possible that some correlations claimed in astrological charts were derived
from observation and validation over a period of centuries.

Obviously astrology is bunk in that planets don't affect you. But it's
conceivable that some claims in astrology are based on evidence that is
actually correlated to birth month and seasons. We would expect to see inverse
correlations for these factors in the southern hemisphere.

~~~
vlasev
While on the topic of astrology, people might find it interesting to read
about IMO the definitive study that shows it's bunk [1]. In it you can see
that they took a lot of "time twins" (people born within a small time window
on the order of hours or minutes) and measure if astrology had any predictive
power over their lives. Spoiler: no, not really. Just a couple of quotes:

"The spacing of human births in a large population is described by a Poisson
distribution, which shows that every year in a city of one million people
about 4,000 pairs of time twins are born 5 minutes apart or less."

"Unlike the Roberts and Greengrass approach (count each time twin against
every other time twin within one day, which would have produced nearly 600,000
pairs), serial correlation counts each time twin once only, thus minimizing
the risk of artifacts. So the test conditions could hardly have been more
conducive to success. But the results are uniformly negative, see Table 2. The
effect size due to astrology is 0.00 ± 0.03."

[1]
[http://www.imprint.co.uk/pdf/Dean.pdf](http://www.imprint.co.uk/pdf/Dean.pdf)

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bobwaycott
Ugh. Can we just stop using the word 'connection' altogether when what we
really mean is 'an indeterminate and quite possibly coincidental correlation
has been found between X and Y'?

A 'connection', to me at least, implies _causality_. No causal relationship
has been found here.

~~~
matt4077
Ugh. Can we just stop feeling like Gods of Statistics because we've read
"Correlation doesn't proof causation" once?

~~~
bobwaycott
Perhaps you should proofread your snark before posting, friend.

I never feel like a god of statistics. My complaint here wasn't even about
statistics. It's not even a specialty of mine. Note my complaint was about
_words_.

The meaning and usage of words, particularly the impressions and messages they
convey to people--the ideas, beliefs, as well as the certainties they
establish and invoke when spoken, written, heard, and read--on the other hand,
most certainly is something I care very much about. There are many areas
outside a probabilistically determined statistical model in which properly
understanding, specifying, and communicating correlation and causality are
useful and important.

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dschiptsov
So, we are getting better with misuse of statistics and media (and
probability).

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randomname2
This could point to different epigenetic programming depending on conception
date, right?

A similar environmental effect was observed with anyone born during the Dutch
hunger winter being significantly more susceptible to certain diseases:

[http://www.news.leiden.edu/news/dutch-hunger-
winter.html](http://www.news.leiden.edu/news/dutch-hunger-winter.html)

------
ExpiredLink
It's certainly a statistical artifact. They probably haven't done cross
validation.

~~~
icegreentea
The paper is linked and free, you could read it yourself.

But you're right, they didn't do full cross validation. They performed a
smaller scale validation where they trained on 80% and tested on 20%. Their
writing is a bit muddled here, but it looks like 12 of the 16 novel
associations (those not previously reported in literature) were validated (as
in passed the above test). They did not perform validation on previously
reported associations that they confirmed - presumably because they drew from
an independent dataset from the original publication, and so this test
constitutes an independent validation of the original study.

------
joefreeman
Would there be any adverse effects on the world if people took note of this,
causing the distribution of birthdays to change so that there was a
significant spike during the May-July low-risk period?

~~~
randomname2
This has only been tested in New York yet. It'd certainly be interesting if
the high/low risk months varied depending on birth location or wherever mom
spends her time during pregnancy.

~~~
blowski
> This has only been tested in New York

That's a very important point. The effect (if it were to be proved) could be
reversed in the southern hemisphere, and completely absent in non-city
environments. I'm plucking those hypotheses out of thin air, but it seems
obvious that the risk goes up because of some underlying reason.

Perhaps being born in New York in October increases the chance that you'll
spend most of your first few months of life in a damp-infested flat without
much natural light. Perhaps it's because of increased stressed levels at
school associated with being one of the oldest in your peer group.

Without knowing the underlying causes, this is just an interesting tidbit.

~~~
vlasev
The conditions are correlated with the changing seasons so it's only logical
to consider things on the other side of the equator. I suspect that all the
effects will be gone around the equator where the differences between the
months are quite small. I'm not sure about the city connections but I think
there have been studies showing people in big cities suffer from more asthma
and so on.

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dghughes
The abstract didn't mention which hemisphere the study was run I'm assuming
the northern hemisphere.

It would be interesting to see a similar study for the southern hemisphere.

~~~
vlasev
From study[1]: "Our dataset includes 1 749 400 individuals with records at New
York-Presbyterian/Columbia University Medical Center born between 1900 and
2000 inclusive."

They also compare some of their data to data from Denmark. So it's all
Northern hemisphere, mid-latitudes.

[1]
[http://jamia.oxfordjournals.org/content/jaminfo/early/2015/0...](http://jamia.oxfordjournals.org/content/jaminfo/early/2015/06/01/jamia.ocv046.full.pdf)

------
richiverse
Would be interesting to see this study done for disease in just children since
their birth month should correlate much stronger with weather and
environmental factors

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amelius
Astrology might have a scientific basis after all...

~~~
flycaliguy
With people in the past living a much more seasonal life, ones in which a
diversity of nutrition can only be provided for babies at different times of
the year, there is a scientific basis that has been explored. Along with food,
babies of the past may have been granted more or less contact with parents
depending on seasonal work loads and so on.

Interesting stuff to think about. Seems to be what this article is getting at.
Imagine how magnified it was when agriculture played a bigger role.

~~~
avaku
I am a scientist and I don't believe in Astrology, and I was always suggesting
this interpretation to my friends who believe in it. Generally, the answer was
"yeah, okay, maybe, I don't really care where it comes from, as long as it's
correlated with the stars". However, they always reject the further conclusion
that in modern times all these effects must have virtually disappeared. Also,
they always confuse statistical correlation with individual people. If someone
is 55% likely to have some trait, while other people are 50% likely to have
that trait, it doesn't really mean you can make a definitive conclusion about
a single person you see. It will only apply if you see 1000 people and do the
average. Just my thoughts. Thanks for yours!

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HenryTheHorse
I do hope they publish the sequel: "Study finds positive correlation between
birth and death"

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oneandoneis2
So, zodiac signs have _some_ meaning after all? :D

~~~
cristianpascu
No, because zodiac signs span on two months. :) They're useless.

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erikb
It seems too early and too surprising to have a reasonable discussion about
that topic to me.

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mziel
Naturally this comes to mind: [https://xkcd.com/882/](https://xkcd.com/882/)

Spurious correlation achieved by misusing statistics. Not to mention
publication bias.

~~~
vlasev
The authors of the study have done as much as they can to eliminate such
effects. Not to mention that the correlation they find for 39 out of 55
conditions has already been demonstrated in the literature.

