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".

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.)

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.

Read the article more carefully and you see they do state a connection between birth month and disease risks. The connections that they haven't found are the specific risk factors caused by the birth month.

The connections that MAY be found might be things like: - November babies getting exposed to extreme cold during the first month of development - Spring babies exposed to high pollen

"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.

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.

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.

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.

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!

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.

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.

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.

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

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.

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

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.

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

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.

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

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

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

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.

I'm looking at the paper, but this was my first thought when I saw

This motivated Columbia’s scientists to compare 1,688 diseases against the birth dates and medical histories of 1.7 million patients treated at NewYork-Presbyterian Hospital/CUMC between 1985 and 2013.

I immediately thought "hmm, tread carefully there fellas."

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?

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.

> 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.

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.

More Cancers and less cancers?

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.

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...

Looks like just one location (NYC)

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

Astrology might have a scientific basis after all...

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.

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!

Be aware that astrology is concerned with character and, if I'm correct, events in your life. Not physical health. And each individual has like a gazillion factors hitting on them throughout their life to change the shit out of the star dust poured on them in the birth room.

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

So, zodiac signs have some meaning after all? :D

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

Only to people who judge articles by their titles :)

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

Naturally this comes to mind: https://xkcd.com/882/

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

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.