This one's for the math whizzes out there

Jen · #1 05-24-2005, 02:35 AM

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madmax · #2 05-24-2005, 02:44 PM

Quote:

Originally posted by ariesrising
Okay, on my multiple births website, I have a lot of statistics.

Over the course of the years I have read a lot of articles about the odds of having identical quadruplets, and most state it's 1 in 11 million or so. Awhile back I figured out how they got that figure, and I used my stats to calculate the real odds at anywhere from 1 in 11.5 million to 1 in 13.9 million (using 6 billion world population, and minimum 43 and maximum 52 sets of identical quads out of around 2500 sets or so...can't be exact on that last number).

Since the stats are always changing, I wanted to update them, only I have NO IDEA how I figured it out before. I've got (I think) all the stats, but can't get the answer, so hopefully someone can help me. I am assuming since I got 1 in 11.5 million using 52 sets before that using 50 now should be around the same, but it's not working out that way.

The stats I now have are:

6.5 billion (world population estimate)
2876 sets of quadruplets in the world (11504 individual babies)
50 of those sets are all identical (200 individual babies)
Quadruplets are (obviously I hope...) a set of 4 babies

Now, I think I have all the numbers I need to get the 1 in whatever stat. And when I used 52 sets ages ago (with a lower world population of 6 billion and lower total sets of quads) it came out to 1 in 11.5 million roughly.

How did I do it??? And did I even do it right the first time?

1. You need to find some new hobbies.

2. I dont think you had it right the first time but I am not going to spend more than 30 seconds on this so I might be wrong. 11.5 million x 52 = 598 million(almost 600 million not 6 billion)

3. What is the "1 in 11.5 million"? Is it 1 person out of 11.5 million people is an identical quad or is it 1 birth out of 11.5 million births results in identical quads. If it is 1 birth out of 11.5 million total births then you need to give us the total number of births, not the total number of people.

CougADPi · #3 05-24-2005, 02:44 PM

From what I have figured out:

2876 quad births:6.5bil people births
thats about 1 : 2.3 mil odds that any given birth would be quads

50 ident. quads : 2876 total quads
1 : 57.5 that the quads will be identical

Ratio of quads to births times the ratio of identical quads to quad births would give identical quads to births (I think):
1 : 14.2mil

I hope this helps (and I have too much time on my hands as well)

KSig RC · #4 05-24-2005, 02:57 PM

Edit: I got bored . . . apparently 3% of births are multiple. So:

6.5b * .97 = 6.305 billion births worldwide (this is an ABSURDLY rough approximation, but it'll have to do)

of that, 50 of those births resulted in identical quads

this means that 1 in every 126,000,000 (that's one hundred twenty six million) births resulted in identical quads.

-RC
--don't make it harder than it is guys

winnieb · #5 05-24-2005, 06:00 PM

-- off the math topic-- just wanted to say the couple a few doors down from me has quads--- two sets of identicals-- boy set/ girl set. they are the sweetest kids-- they are 9yrs old now.

/hijack!

Tom Earp · #6 05-24-2005, 06:55 PM

How about = 0. If not they should not promegete!

Taualumna · #7 05-25-2005, 02:11 PM

Interesting you posted this, ariesrising...

Quote:

HOUSTON - A Houston woman has given birth to a set of rare identical quadruplets, conceived without fertility drugs or in vitro fertilization. They are among fewer than 50 such sets ever recorded.

ADVERTISEMENT

Two of the four babies born two months ago — three months prematurely — may get to go home this week, where their 15-month-old brother awaits them

http://news.yahoo.com/s/ap/20050525/...al_quadruplets

bekibug · #8 05-25-2005, 06:41 PM

A woman in the Tuscaloosa area gave birth to identical quads a few months back. The girls were so cute! The parents dressed each one in only one color (pink, yellow, purple, minty green) and painted their toenails those colors to tell them apart. The couple already had 4 children (both had divorced and remarried). I couldn't imagine having 4 children already and then another 4 come along!

FirstAndFinest · #9 05-25-2005, 06:48 PM

I wonder what the probability is for a non-multiple birth adult having a multiple birth without fertility help? Or, for that matter, what the odds are that a multi-birth adult will have a mulit-birth?(The article mentioned that the Houston woman was an identical twin, herself.)

AKA_Monet · #10 05-25-2005, 07:49 PM

The twinning phenomenon...

For true genetically identical siblings--apparently, there is a massive build up of DNA in the zygote that causes it to split 4 ways initially rather than 2. That is within the 1-2nd hour after conception... Within 4 days after conception, the embryo starts to form. By the 2 week, the embryo ought to implant into the uterus barring any problems...

I think I was taught that the ovum did not finish the last step in meiosis and is still diploid rather than haploid. How one haploid sperm inseminates a diploid egg is unknown to me, at least. But it is not suprising that this occurs in human--because it does in many other sexually reproducing organisms, including mammals.

Of course a sperm can be diploid also, or double headed--but that has not been shown to be effective for appropriate implantation and impregnation--usually causes miscarriages...

I think when a woman's eggs are older, there are more than enough DNA stuck in them... So most women who have multiples without fertility drugs might be older if they were able to give live births...

I have only seen 1 woman in New Mexico that had identical quads boys. That was a trip.

And I have seen identical triplets.

Whether or not at that time they are truly genetically identical was unknown... But that's another story.