Spotting patterns in birthdays

[andrewducker]

from

The basic one of "When it's cold outside people stay in and have sex" is fairly obvious.

But laying things out like this, you can see the faint horizontal line that shows that nobody wants to give birth on the 13th.

And that medical staff _really_ don't want to work at Christmas. Or Independence Day.

Comments

[momentsmusicaux]

Might the big white column in November be Thanksgiving? (I don't actually know when that is, just guessing.)

[adrian_turtle]

you can see the faint horizontal line that shows that nobody wants to give birth on the 13th.

That also includes reporting errors. A friend of mine was born around 1am on the 13th of the month, more than 40 years ago. Her birth was officially recorded as being on the 12th of the month. The person at the hospital who certified such things presumably wanted her to have an auspicious start, and her parents were kind of distracted at the time. (Her own child actually was born on the 12th of the month. A different month, obviously.)

[pseudomonas]

For February babies, there seems to be a desire to have them on Valentine's Day.

[sinpar]

Fascinating stuff.

[cangetmad.livejournal.com]

Depressingly high evidence of elective Caesarians - look at Valentine's Day as well as the holiday periods.

[andrewducker]

32.8% apparently.

And thanks, I hadn't spotted Valentine's Day as being even higher than the ones around it.

[brixtonbrood.livejournal.com]

32.8% is the total CS rate, not the ELCS rate, (which for some reason I can't track down). Most CSs are "emergencies" following issues in labour and therefore unaffected by date preferences except insofaras they are more common following induction.

(Although I was offered a choice of birth date during my EMCS, but that was because it was 11:59 pm at the time.)

[cangetmad.livejournal.com]

Also hadn't noticed til now how the "holiday period" light days are followed by very dark ones - my daughter's December 30th birthday is obviously a popular "choice" for people keen to avoid actual holidays clashing with birthdays. And to think I achieved that purely by accident.

[brixtonbrood.livejournal.com]

That's partly why Valentine's Day is so dark - it's a combination of "ah, Valentine's Day would be sweet" and all the pent up demand from the 13th the day before.

[redshira.livejournal.com]

Yep; I was due on Feb 12th, but as my mum had been told she'd need a C-section, she chose the 14th "so the postman would think she was popular".

[brixtonbrood.livejournal.com]

Not just ELCS, inductions would lead to that pattern as well.

[cangetmad.livejournal.com]

Ah, 'course, yes.

[rhythmaning.livejournal.com]

I think I'd have expected a peak in the spring, too - after all those summer romances.

[bookzombie.livejournal.com]

I'm kinda surprised there isn't a bigger peak in November - 9 months after Valentines (I'm almost certainly a Valentines baby!)

[aiela.livejournal.com]

My birthday is October 2nd, and i've always been told that early October is busy because of NYE. (I was actually due 10/31, so I'm not a NYE baby.)

[simont]

It's a shame the data only gives rank and not absolute frequency figures. I was hoping to use it to work out the real answer to how many people you need in a room before there's a better than 1/2 chance of a shared birthday.

(The usual answer of 23 assumes all possible birthdays are equiprobable. If I remember rightly, any divergence from that will reduce the figure even further.)

[andrewducker]

It makes sense to me that if people cluster, the chances of them being together is higher!

[henriksdal.livejournal.com]

this sort of thing? It's an update linked at the source article



but he only has that set of data

[cartesiandaemon.livejournal.com]

Don't forget to include the chance that two identical twins are there together (obviously that depends on the sort of room: a classroom sorted by surname is very likely, an arbitrary coffee shop is less likley :)).

[ipslore.livejournal.com]

Also, the week-long block of Thanksgivings.

[aiela.livejournal.com]

I am going to show this to my coworkers - we have a long standing thing about how we never have any employees with November birthdays (we do birthday celebrations) and this shows why - November birthdays are far less common.

[camies.livejournal.com]

That's odd because I'm a November birthday and I have a whole lot of friends who were born in November. That and February are the clusters among my lot.

[widgetfox.livejournal.com]

I continue to be enchanted that Prince Charles was born nine months after Valentine's Day.

[davidcook.livejournal.com]

I'd love to see an Australian / Southern hemisphere version of this - our winter doesn't align with the Christmas/NY holiday period, would be interesting to see where the peaks are.

[andrewducker]

If you find one, I'd love to see it!

[barondave.livejournal.com]

The data was births from 1973-1999 so I'm technically not on it. Still, my birthday (4/13) is on one of the lighter days. My mother claims I was "nine months to the day" after their marriage, and they had a summer ceremony.

[akicif.livejournal.com]

Neat! It'd be nice to have day of the week info too, though.

[andrewducker]

Yes, that would be fascinating!

[camies.livejournal.com]

I was born in mid-November so would appear to be a Valentine's baby - but was born a month prematurely so was conceived in March. Premature birth runs at 8 to 12 percent in the 'developed' world - enough to skew the figures I would think.

[pr1ss.livejournal.com]

You may also be able to find statistics for day of the week, or time of day. Late afternoon on Fridays, and just before shift changes tend to influence the surgical delivery rate. Doctors even admit to this. They say that they don't want to leave someone they have been attending, for their colleagues on the next shift to have to deal with.