For unto us a child is born

December 25, 2013 5:53 AM

According to statistician Aki Vehtari of Aalto University in Finland, there is diminished 20% chance that today, December 25th, is your birthday. There is a 5% higher likelihood than chance that your birthday is actually February 14th.

Vehtari's decomposition of the birthdays data (the number of babies born each day in the United States, from 1968 through 1988) using a Gaussian process model,

posted by roomthreeseventeen (27 comments total)

Basically what the graphs mean is that if you can make sense of them you drank moderately yesterday. Congrats!
posted by Foci for Analysis at 6:36 AM on December 25, 2013 [4 favorites]

I wonder how much of an impact is "scheduled c-sections are not scheduled for holidays or weekends" -- my friend, for instance, knew that if she were going to be induced she would be induced on a Monday or Wednesday because those were the days the doctor had for non-emergencies.
posted by jeather at 6:45 AM on December 25, 2013 [1 favorite]

Having been extracted via c-section on a Christmas Eve some years ago, I can confirm that this is probably true.
posted by Flashman at 6:58 AM on December 25, 2013

Birthdate frequency, previously.
posted by Horace Rumpole at 7:02 AM on December 25, 2013 [1 favorite]

Proving once again that Jesus' existence was highly unlikely.
posted by goethean at 7:06 AM on December 25, 2013 [12 favorites]

They're always going to hurry you along before the holidays if you're already vergin'.
posted by pracowity at 7:07 AM on December 25, 2013 [2 favorites]

Is that where the phrase "vergin' birth" comes from?
posted by ZenMasterThis at 7:09 AM on December 25, 2013 [5 favorites]

With the prevalence of induced births (not just c-sections) these days I'm surprised it's not closer to 90%.
posted by ook at 7:49 AM on December 25, 2013 [1 favorite]

I was born on Christmas in that era. Which is to say, Happy Birthday to Me! and my slight statistical unlikelihood.
posted by hydropsyche at 8:05 AM on December 25, 2013 [3 favorites]

Circumstances required a c-section. Mine was scheduled for the date I was due, July 28. When my little sis came along, the due date was predicted to be July 4, so they scheduled her c-section for July 2 so the doc could get out of town. That was the stated reason.
posted by MsDaniB at 8:12 AM on December 25, 2013

Apparently, my oldest's Christmas Eve birthday is quite rare; I only know one other person that shares her birthday.
posted by _paegan_ at 8:18 AM on December 25, 2013

But what is the likelihood of shepherds sleeping out on the range at the start of winter In Palestine?
posted by eustatic at 8:21 AM on December 25, 2013

somewhere out in the void, a lone star winks out.
posted by benzenedream at 8:26 AM on December 25, 2013

I have two cousins born on December 23 and one born December 24. HAPPY BIRTHDAY ALL MY HOLIDAY COUSINS!
posted by ThePinkSuperhero at 9:01 AM on December 25, 2013

My favorite birthday related statical problem, aptly named the Birthday Problem, gives a 50% likelyhood that if there are 23 people in a room two of them share a birthday.
posted by Quack at 9:16 AM on December 25, 2013 [1 favorite]

In my case, there's a 100% chance my birthday is February 14th.
posted by chavenet at 9:30 AM on December 25, 2013 [4 favorites]

Is that where the phrase "vergin' birth" comes from?

The guy who explains the (obvious) joke gets the favorites?
posted by pracowity at 9:39 AM on December 25, 2013 [4 favorites]

My brother was born January 9th and vowed to never have a child born near xmas.
His second was born xmas day. Child gets cake and cards on bday and cards and presents June 25th.
posted by mightshould at 12:16 PM on December 25, 2013 [1 favorite]

Quack- when I present the birthday problem to students, they usually find it more amazing that there is around a 97% chance of at least two people having the same birthday if there are only 50 people in the room. In other words, if you bet a friend that there are two people in the room with the same birthday anytime you are at a party with at least 50 people, you will win that bet almost every time!
posted by wittgenstein at 12:49 PM on December 25, 2013

The guy who explains the (obvious) joke gets the favorites?

This is MetaFilter's equivalent of responding to your pun with the sad trombone sound.
posted by straight at 1:07 PM on December 25, 2013 [2 favorites]

I can present an even unlikelier statistical scenario: my twin sister and I were born on Christmas Day. Happy Birthday to us! (And to hydrosyche)
posted by LN at 4:05 PM on December 25, 2013 [1 favorite]

I mentioned this in metatalk but my new grandbaby was just born on the 23rd (less than an hour before midnight, thus missing Christmas Eve by a slim margin.) Which made one of my Facebook friends very happy-he was rooting for her to be born on HIS birthday.


My son AND his wife (the new parents) both had their birthdays this past Thanksgiving. One of my daughters occasionally has a birthday on Easter. And my husband's birthday is the day after Valentine's Day. (To say he is glad I no longer work for a florist is an understatement.)
posted by St. Alia of the Bunnies at 5:16 PM on December 25, 2013 [1 favorite]

I'm 100% sure my sister was born on Christmas morning when I was 6. And I was born on Valentine's Day. We have another sister in between us who didn't have a fancy birthday like we did, she was born June 13th and when she was a kid I told her she was born on Friday the thirteenth, and our parents couldn't remember if that was true. Then she got old enough to look it up. She's never liked me much.
posted by mareli at 6:12 PM on December 25, 2013 [2 favorites]

If it's about scheduled c-sections, then you'd think that the increase in births on the days preceding and following the holidays would make up for the decreases on the actual days. That seems like it might be the case for Christmas (looking at that graph), but not for July 4th. Any explanations?
posted by lollusc at 6:44 PM on December 25, 2013

I am 100% likely to have been born on Christmas, as was my best friend. I greet all my co-birthdayists in this thread too. (Did it suck for you too?)
posted by rodii at 10:40 PM on December 25, 2013 [1 favorite]

Even Jesus probably wasn't born on Christmas.
posted by pracowity at 2:02 PM on December 26, 2013

If it's about scheduled c-sections, then you'd think that the increase in births on the days preceding and following the holidays would make up for the decreases on the actual days. That seems like it might be the case for Christmas (looking at that graph), but not for July 4th. Any explanations?

They actually do talk about that in the comments. It seems that the bumps before and after may have been smoothed inadvertently with the seasonal effect and the creator will try to take that into account in future versions.
posted by LizBoBiz at 7:56 AM on December 27, 2013 [1 favorite]