"A couple who share the same birthday were stunned when their first son was born on the same day - at odds of 1,014 to one"
As far as I can make out, the odds of the child sharing the same birthday as the parents is 365 to one. The odds of all three sharing the same birthday would be 365 squared (133,225 to one).
1014 *might* be the probability that 3 people share the same birthday.
However, it's equally valid to argue that "given these particular parents have a shared birthday on date X, what is the probability that their child will be born on date X" which is 1/365 or 1/366 for a leapyear.
Which is an excellent illustration of how you can talk bollocks with stats :)
Not the same problem. That's about the odds of people in a group sharing a non-specific birthday. This is either about the child sharing the parent's birthdate or the odds of just them all having the same specific date.
1) An arbitrary 2 parents + one child share a single birthday;
of
2) This specific couple have a child who share's their birthday (their birthdays already being an established event and thus having a probability of 1
As I said in my other post, subtle phrasing and some misplaced assumptions make a factor of 3 difference to the result. And we have a self selected generally smart bunch of people interpreting it in different ways, so imagine how easy it is to pull the wool over the general population's eyes!
365 x 3 -1 It's quoted above your reply. (Immediately before it.) I shal write this very slowly then go over it to make sure you get it:
365 = the number of complete days in a year. I added three years together to make 1095. Then I found I was stuck with it (1095) But I managed to get it down to 1094 by carefully adding the odds to the sum.
Which was a minus number, that is: I had to add in a "minus number" (called One or "1" in this case, in maths.)
I had derived that number from the chance being one more than the rest (the others being the parents.)
That was the number I was referring to. Do you have the same problem analysing computer systems? I appreciate that 1014 was not a viable number and was trying to find a more viable alternative. We tend to do that sort of thing in this country. My problem in understanding you is that I don't know what country you come from.
I have heard that in a certain part of the Amazon, otherwise perfectly good engineers don't count in linear sequences. Do you come from Peru by any chance?
Please don't think I am belittling you. I actually wish that I could count in logarithms.
I appreciate that you've lost your tinfoil hat but even so, you should be able to understand the original question and not invent a method of reaching a figure plucked from the aether rather that the quoted figure.
Still, if it amuses you feel free to derive means to arrive at other irrelevant numbers.
I don't mean to belittle you as I appreciate that without meds, your thinking is disordered.
The article was in yesterday's Sun, and also contains the words "Ladbrokes confirmed the odds of Aidan sharing his birthday with not one but both parents were 1,014 to one". It sounds as if Ladbrokes have multiplied the odds for both parents having the same birthday, with odds for sons having the same birthday as the mother, neither of which are likely to be 1 in 365 in actual practice.
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