• workerONE@lemmy.world
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    5 months ago

    With 8 billion people alive I refuse to believe there is any statistical difference between days of the year. For example according to this infographic my birthday is one of the most common but the days before and after are not?

    • ChaoticNeutralCzech@feddit.org
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      5 months ago

      The color scale is terrible. Here is a more credible chart based on presumably the same data by Social Security Administration, covering 62,187,024 US births (2000-2014).

      Meanwhile, the post’s chart’s actual Reddit OOP is u/plotset, an account made to shill PlotSet.com, a data visualization software.
      They had this to say about the data:

      This data represents 4,153,303 US-born babies only between 2000 and 2014.

      Top 10 Most Common: Sep 12 (0.307%) Sep 19 (0.306%), Sep 20 (0.302%), Dec 19 (0.300%), Sep 10 (0.300%), Dec 20 (0.299%),Sep 18 (0.299%), Aug 8 (0.299%), Sep 26 (0.299%), Sep 17 (0.298%)

      Top 10 Least Common: Dec 25 (0.155%), Jan 1 (0.186%), Dec 24 (0.193%), Jul 4 (0.212%), Jan 2 (0.231%), Dec 26 (0.238%), Nov 23 (0.238%), Nov 25 (0.240%), Nov 27 (0.241%), Nov 24 (0.241%)

      Data Source: Kaggle.com/datasets/ayessa/birthday

      Tools: PlotSet.com

      Note that the “4,153,303” figure is bullshit. It is close to births per year but does not actually correspond to the sum in any of the 15 years, nor the average.

      Also, neither chart normalizes by weekday: 3 of the years in question started on Tuesday and Saturday while only 1 on Friday, causing most of the variation that got amplified by OOP’s terrible color range. (Because of leap years, I made a table of most common starting weekdays for each month; see my other comment. For example, one of the most common birthdays, August 15, was more often Wednesday or Friday than Saturday.) Without doing weird math, one can ensure the effect of weekdays is largely mitigated by using data from 28 consecutive years, which I believe can be pieced together from several good online sources but I’ll be leaving that as an exercise to the reader.

      • mal3oon@lemmy.world
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        5 months ago

        This absolutely varies by country/culture, not drastically, but you will see different patterns

      • Johanno@feddit.org
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        5 months ago

        So it is about average for almost all days. You have more births in fall, probably because of more sex in winter.

        And it seems women really don’t want to birth on important holidays. I didn’t think that the power of will is that strong.

        • ChaoticNeutralCzech@feddit.org
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          5 months ago

          Don’t forget the weekdays. The total births in the dataset by weekday are:

          SUN |||||||||||||||||||||||| 5886889
          MON ||||||||||||||||||||||||||||||||||||| 9316001
          TUE ||||||||||||||||||||||||||||||||||||||||| 10274874
          WED |||||||||||||||||||||||||||||||||||||||| 10109130
          THU |||||||||||||||||||||||||||||||||||||||| 10045436
          FRI ||||||||||||||||||||||||||||||||||||||| 9850199
          SAT |||||||||||||||||||||||||| 6704495

    • MindTraveller
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      5 months ago

      September births are more common because of christmas sex

    • frickineh@lemmy.world
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      5 months ago

      Yeah, everybody’s parents are fuckin between Thanksgiving and New Years.

      Anecdotally, I knew that years ago. I worked in a call center and got so bored that I’d mark the day in my yearly calendar when a customer had that birthday, and September and August filled up quick and had so many duplicates. Took me forever to fill up winter, though.

        • frickineh@lemmy.world
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          5 months ago

          Do you mean for the sex or giving birth? For the former, I’m guessing that’s why there’s a bump in December. For the latter, I wouldn’t be surprised if people made extra effort to give birth on valentine’s day. Plus, sex can induce labor if you’re close.

  • Binette@lemmy.ml
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    5 months ago

    It surprises me that there are a lot of births on valentine’s day.

    Like 9 months later? Sure. But this? Nah.

    • ISOmorph@feddit.de
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      5 months ago

      I garantee you it’s crazy people planning their sexy time accordingly and then pushing for a c-section cuz it’s romantic

    • ralakus@lemmy.world
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      5 months ago

      Also interesting to see how few births there are around Christmas.

      “Can you hold it in just two more days, honey? Don’t wanna ruin this year’s celebration.”

      • OminousOrange
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        5 months ago

        Hospital staffing and delivery management are more likely the causes. If the risk is low, they’re less likely to start an induction on those days.

  • IninewCrow
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    5 months ago

    Also discovered something crazy about birthdays when it comes to athletics and competitive sports.

    An athletes chance of success are based on what month they are born. Depending on the sport, region and organizations and systems involved … if an athlete is born earlier in the year and the rank they are placed in starts at the beginning of the year, they have a better chance because they will almost be a year older than the player born at the end of the year. In Junior leagues or youth divisions at 10 years of age to 18 … a year makes a huge difference in the players.

    I learned all of this from talking to a few individuals who went through provincial level hockey in Ontario.

    When it comes to the top level sports … what month you are born really matters.

    • OminousOrange
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      5 months ago

      This matters in education too. Malcolm Gladwell did a bit of a study on it.

      Makes sense though. In anything that is segregated by year, the oldest in one cohort is going to have nearly a full year more development than the youngest.

  • prime_number_314159@lemmy.world
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    5 months ago

    The high period before/after Christmas so that more of the medical community can have Christmas off is pretty strong.

    I have no idea why August has such a strong weekly cycle, when July/September aren’t that clear. I mean… surely weekend vs. weekday is canceled out by having multiple years that people are born in. If someone knows, I’d love to hear the answer.

    • ChaoticNeutralCzech@feddit.org
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      5 months ago

      The color scale hugely amplifies minor differences, see my other comment. In the dataset, 15 years (2000-2014) are represented and the weekly cycle is therefore present. This could have been mitigated by using a 28-year dataset. Here is how often each month started on a given day in the dataset. We don’t have colored text so I used emoji.

      01/ JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
      SUN 2➖ 2➖ 1🔻 3⚠️ 2➖ 3⚠️ 3⚠️ 2➖ 2➖ 2➖ 1🔻 2➖
      MON 2➖ 1🔻 2➖ 2➖ 2➖ 1🔻 2➖ 2➖ 3⚠️ 3⚠️ 2➖ 3⚠️
      TUE 3⚠️ 3⚠️ 2➖ 3⚠️ 3⚠️ 2➖ 3⚠️ 2➖ 1🔻 2➖ 2➖ 1🔻
      WED 2➖ 2➖ 2➖ 1🔻 2➖ 2➖ 1🔻 3⚠️ 2➖ 3⚠️ 2➖ 2➖
      THU 2➖ 2➖ 3⚠️ 2➖ 3⚠️ 2➖ 2➖ 2➖ 2➖ 1🔻 3⚠️ 2➖
      FRI 1🔻 3⚠️ 2➖ 2➖ 1🔻 3⚠️ 2➖ 3⚠️ 2➖ 2➖ 2➖ 2➖
      SAT 3⚠️ 2➖ 3⚠️ 2➖ 2➖ 2➖ 2➖ 1🔻 3⚠️ 2➖ 3⚠️ 3⚠️

      Here is how likely any date is to be Monday-Friday in the data (out of 15):

      How often Mon-Fri JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
      01/08/15/22/29 10🔻 11➖ 11➖ 10🔻 11➖ 10🔻 10🔻 12⚠️ 10🔻 11➖ 11➖ 10🔻
      02/09/16/23/30 11➖ 12⚠️ 12⚠️ 10🔻 11➖ 11➖ 10🔻 11➖ 10🔻 10🔻 12⚠️ 10🔻
      03/10/17/24/31 10🔻 11➖ 11➖ 10🔻 10🔻 12⚠️ 10🔻 11➖ 11➖ 10🔻 11➖ 11➖
      04/11/18/25 10🔻 10🔻 11➖ 11➖ 10🔻 11➖ 11➖ 10🔻 12⚠️ 10🔻 11➖ 12⚠️
      05/12/19/26 11➖ 11➖ 10🔻 12⚠️ 10🔻 11➖ 12⚠️ 10🔻 11➖ 11➖ 10🔻 11➖
      06/13/20/27 12⚠️ 10🔻 10🔻 11➖ 11➖ 10🔻 11➖ 10🔻 11➖ 12⚠️ 10🔻 11➖
      07/14/21/28 11➖ 10🔻 10🔻 11➖ 12⚠️ 10🔻 11➖ 11➖ 10🔻 11➖ 10🔻 10🔻

      You can see for example that August 01/08/15/22/29 is 10-20% more likely to be a workday than other days, which corresponds to the extra births. Feb 29 cannot be read directly from this table; its value is 3 out of 4 (2000: Tue, 2004: Sun, 2008: Fri, 2012: Wed).

      As for your question: every month has approximately the same strength of the weekly cycle, it’s just that the prevailing colors in July-September show them the most. August’s is more visible because it does not have the disrupting July 4 and September 11.