Tuesday, 27 August 2013

What Are the Chances? (in Postcrossing)

I received a very familiar-looking postcrossing card in the post today. The front was unmistakable (see below), but after all São Paolo is a big city and the carneval famous, so not too surprising that more than one postcrosser might choose to send that card.

BR-271063-001BR-271063-002

(I divided the image into two to be able to show it as big as possible here.)

What was remarkable, however, was that when I turned both cards over, and compared the backsides… Those were identical too, apart from the date:

BR-Sao Paolo x 2

The sender was of course the same person as well.
I’m just really curious about how common (or rare) that might be! (I know this is probably not the right place to ask the question and get a good answer; I just could not resist showing you.)

PS.  I see from comments that I need to explain further. In postcrossing, you don't write repeatedly to the same person. (If you do, then it's by private agreement and outside the system.) When you get a postcrossing address to write to, it can be anywhere in the world, among over 400 000 members. You don't get to give preferences in that respect. The addresses are distributed randomly (or based on a number of various factors automatically calculated). Each card has a unique ID number. The odd thing is not that this postcrosser sent the same card twice, but that she got my address twice within a month.

11 comments:

Mersad said...

Maybe the person bought a bunch of them to send out, and shipped it twice to you.

Mersad
Mersad Donko Photography

MadSnapper said...

I agree with mersad, someone did what i sometimes do, double send, double work... it is a beautiful card, great idea to break it up like that.

DawnTreader said...

Mersad and Sandra: I see from both your comments that I need to explain further. In postcrossing, you don't write repeatedly to the same person. (If you do, then it's by private agreement between the two of you, and outside the "system".) When you get a postcrossing address to write to, it can be anywhere in the world, among over 400 000 members. You don't get to give preferences in that respect. The addresses are distributed randomly (or based on a number of various factors automatically calculated by computers). Each card has a unique ID number that the recipient must register when he/she receives it. The odd thing is not that this postcrosser sent the same card twice, but that she got my address twice within a month. The two cards each have their own unique ID.

Librarian said...

I am sure someone can (and will!) come up with a mathematical explanation of how high the probability of this happening is, Monica.
RJ could do it, no doubt, but I am not going to ask him when I'll see him again tomorrow morning at our customer's; it would only mean at least half an hour's worth of equations scribbled on the whiteboard above his desk instead of getting started on the day's tasks :-)
He just LOVES such questions, and to answer them thoroughly, and he loves scribbling on his whiteboard when he explains something to me (or to our customer)!

DawnTreader said...

Oh by all means Mekie, do NOT forward the question to RJ... I was not really expecting an answer, just sharing my surprise ;) There is a forum at the postcrossing site that I've not yet explored, I might take the question there just to find out if the same thing has happened to others.

Ginny Hartzler said...

Yes it IS strange. But what an gorgeous card, it is just perfect for this venue. It is probably my favorite I have seen so far.

Jenny Woolf said...

I can't explain ... but what a wonderful card. Well worth looking at twice :)

SandyCarlson said...

That's wild! Very interesting. Postcrossing sounds interesting. I would love to get involved.

VirginiaC said...

Well what are the odds? If only that were the lottery.
Loved the card, it's very detailed.

HansHB said...

Great post, nice to study the details!

Graham Edwards said...

I suspect that each time the draw is done it is statistically unique and therefore that the odds are about 400,000 to 1 (assuming that every person is allocated an address)..

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