I know you are being ironic, but for those that don't, this is completely unrelated to Astrology and more to how we break kids/teens in age categories (sorry, I don't know the proper terms for this in English). Which, by the way, may be different from country to country due to terms/calendars, etc.

I had a thought that astrology may have had some merits in older societies in climates where weather and daylight patters have distinct variations throughout the year (i.e tropical excluded zones), with effect on agriculture and daily activities, and so how and what small child were exposed in specific several months of their life (diet, activity, temperatures, daylight, ...) have had noticable effect on their behaviour and growth. I.e. if mothers' breastmilk composition varies based on the availability of fresh and nutritious food, or if nutritious food was available at the time of weining, or at their growth spurts, how much outside activity they had after learning to walk or run, what they seen mostly while learning to see, and so on, so the variations in the weeks and months when specific bodily and neurological development occur, that may have been noticable. Winter childs are so, spring childs are different so, and so on. Modern societies equal these yearly variations a lot, even if astrology hocuspocus had some foundation due to such underlying real resons, it likely disappeared in past several decades.

This is the thing. Astrology can more accurately be described as _earthstrology_. The qualities are reflected from the fixed perspective of the equinox and solstices, per the northern hemisphere. There's no relationship to the constellations as is commonly understood; it's planetary positions interfacing with the seasons, and the symbols generated from such.

Yeah, I wrote my post as a joke, but I think that before modern medicine it would have been measurably better to be born in the autumn, so that your mother would have fresh produce in the most important months of fetal development.

The USAH ADM coach training now addresses this directly. They require all youth hockey coaches to take self-paced and live workshop training, and require annual continuing education.

One example here that explains the thought process:

"Birthday bias: Understanding relative age effect in youth hockey"

https://www.admkids.com/news_article/show/823923

Well, I don't think that table is sufficient to show your point.

Trivially if more individuals were born in Feb/Jan then you should expect more players to be born then. This is not the case, Feb/Jan are the 12th lowest and 10 lowest birth months (for 2023 [1]; I suspect things stay fairly in line across years).

So, while comparing apples-to-oranges, if you divide the number of players by live births you see it start at 0.3% in Jan and pretty linearly drop down to 0.18% in December.

[1]: https://www.cdc.gov/nchs/nvss/vsrr/provisional-tables.htm

This study tested sun-sign (which is basically birth month I think) against personality tests for predicting life outcomes and found that sun sign did very poorly compared to the personality tests. I'd have thought there would be a small chance of birth month predicting some things, and then adding in other astrological facts (the position of Jupiter or whatever) would make things worse, but both methods appear to be equally bad.

Is that astrology or just the time of year? I.e., is the cause the position of a planet projected onto the plane perpendicular to your position at birth or some process with a strong 1/year frequency component?

Arguably, birth date and astrology are only tangentially related. Iirc I looked into it and there was little empirical evidence for 12 groups, it is more like 4 groups spring/summer/fall/winter.

I think it was a joke. The statistical factor is actually age: the older kids perform better because they're more grown up (physically bigger, mentally more developed).

So if you set a cut off point at September, for example, kids born just after September: October, November, December, will be the biggest ones.

For example for an age group covering up to 11 years old in September 2024, the kids that are 10 years and 9/10/11 months old (so born in October, November, December 2013) will statistically be the best players of their group.

Anything can potentially affect anything. So, sometimes correlations of different things, will occur due to that.