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Author Topic: The science of birthdays?  (Read 5354 times)

Offline glovesforfoxes

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The science of birthdays?
« on: 05/01/2010 02:09:29 »
When thinking about birthdays, I'd taken for granted the assumption that you have an equal chance of 1/365 having a birthday on any day of a normal, non-leap year, from the perspective of the chance of a baby born anywhere in a particular hemisphere. However, are there are any reasons we can challenge this assumption? It seems to make more sense to me that there would be several factors to take into account when people would have birthdays.
Birthdays must also be counted for people that are dead, since if they are predisposed to die at certain times of the year it would skew the results for newly borns (say, as the result of winter & a particularly virulent seasonal flu)

This is a pretty hard task, at least to single out just one particular factor that would influence where a cluster of birthdays would occur. I've heard that Spring causes people to fall in love more easily, & that there's a physiological mechanism for this involving light & some chemical in the brain, but I've forgotten the important details. From this, you'd expect higher birth rates in winter time - is this the case, & are there any other seasonal, or even on a shorter timescale (like variation in days) that would uniformly affect mothers giving birth?





 

Offline Geezer

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The science of birthdays?
« Reply #1 on: 05/01/2010 02:51:50 »
I'd like to try to answer your question. Perhaps you could make it more explicit?
 

Offline Bored chemist

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The science of birthdays?
« Reply #2 on: 05/01/2010 09:05:15 »
I understand that people are more likely to die in the Winter.
You could do a set of Google searches for each day of the year with the word birthday or born and see how many hits you got. The trouble is that, for example, the 14th of march will get a lot of hits because it's Einstein's birthday.
 

Offline glovesforfoxes

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The science of birthdays?
« Reply #3 on: 05/01/2010 09:57:01 »
It's difficult to describe as it is, but at 2am it was even harder!

There should be, assuming there are no influences on when women give birth, an equal chance of any single baby being born at any time of the year so a 1/365 chance of being born on any particular day in a non-leap year. I'd like to know if there are dates or periods of time when women give birth more or less, & correspondingly people's birthdays would cluster around a certain point (i.e winter - there are 7 birthdays coming up on the same day this January!) & if there are any scientific explanations or mechanisms describing how these affect giving birth. The way I see it, there should be variables that affect all years where women give birth, & there should be variables in those years too - say if we have a particularly hot summer, maybe people had more sex, leading to a higher corresponding rate of conception. I'm interested (if they exist!) in the variables in years & also outside of years.
 

Offline BenV

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The science of birthdays?
« Reply #4 on: 05/01/2010 10:21:21 »
So essentially, what are the factors that influence rate of conception in a population?

Good question!
 

Offline Variola

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The science of birthdays?
« Reply #5 on: 05/01/2010 10:40:00 »
Hmmmm off the top of my head

Weddings- couples like to wait until after they have had their big day and honeymoon before trying to conceive. That means if most people get married in the Summer, then the following Spring will see an increase in births.
Holidays- the nice warm sun, balmy evenings, no work in the morning etc lead to an increase in sexual activities between couples, ergo increasing the chance of conception.

Christmas/New Year- many babies are conceived while the parents are a touch tiddly! Christmas and New Year are times when such festivities are quite common! Also again some women like to get the celebrations and associated alcohol consumption out the way before trying for a baby.
Also on a less positive note, contraception if often forgotten during festivities, and emergency contraception is not as available as doctors/chemists are closed.

I do still believe there is a primal urge to reproduce once Spring is here, I have 2 Winter and one Autumn baby so that is my excuse!!  :)
 

Offline Chemistry4me

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The science of birthdays?
« Reply #6 on: 06/01/2010 03:20:33 »
In a group of 23 people, the probability is just over 50% that two people will have the same birthday.  For 57 people, the probability is more than 99%.
Now that I would never have thought!
 

Offline Geezer

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The science of birthdays?
« Reply #7 on: 06/01/2010 03:39:21 »
In a group of 23 people, the probability is just over 50% that two people will have the same birthday.  For 57 people, the probability is more than 99%.
Now that I would never have thought!

It's true. That's why bookies can make a lot of money. Good bookies really understand probabilities.
 

Offline Geezer

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The science of birthdays?
« Reply #8 on: 06/01/2010 04:09:38 »
Ah ha! Now we know how DiscoDave made his money.
 

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The science of birthdays?
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