Tuesday, November 29, 2011

The Tuesday boy problem, in under 300 words

I saw a post this morning about something called the "Tuesday Boy Problem". It illustrates a really interesting and counterintuitive topic in probability, but it was written up in a frustratingly verbose, confusing, and ambiguous way. So I'm going to try to restate it more clearly.

Let's start from the basics. If a person on the street says to you, "I have two children," what is the probability that they're both boys? 1/4, since there are four possibilities, one of which produces two boys:

Now, imagine he says, "I have two children, and at least one of them is a boy." What is the probability they are both boys? Strangely, 1/3: we eliminate one of the four possible universes from the previous diagram, and one of the remaining three has two boys:

Here's where it starts getting strange: Let's say he says, "I have two children, and at least one of them is a boy born in an even-numbered month." You'd think that the information about his birth-month would be irrelevant, but believe it or not, it actually matters. We cross off 9 of the 16 possible worlds, and of the remaining 7, there are 3 with two boys. To put it another way, the even-month information eliminated half of the previous table's GB and BG universes, but only a quarter of its BB ones. So the odds are 3/7:

Finally, to return to the original problem: If the man says, "I have two children, and at least one of them is a boy who was born on a Tuesday", the probability that both are boys is a bizarre 13/27:

Kinda looks like a Scandinavian flag.

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Monday, March 21, 2011

Wild rumor: Conde Nast thinking of granting independence to reddit?

According to the Wall Street Journal's All Things Digital, Conde Nast is considering a spin-off of reddit.

This is the first I'm hearing of it, and it's being denied by the current admins, but I hope there's a grain of truth to the story.

Spinning reddit off would be a brilliant move, a total no-brainer. There are exactly zero synergies between reddit and any other Conde Nast property, and the site gains nothing from Times Square oversight. In fact, it would flourish even faster and more fully if freed from the policies that have been strangling it for years. ("Why does a site with a billion pageviews a month need more than one salesperson?" "What do you mean you want a $200 SSD hard drive? Anna Wintour gets by without one." "You want the company to pay airfare and hotels for your programming candidates? No way; BonAppetit.com just hired a perfectly good web designer without having to do that.") And imagine the motivating power of employee equity, which would actually be possible if reddit were an independent company.

The part of the rumor that makes no sense is where the Newhouse family is supposedly going to be selling big chunks of this spun-off company. In my time at reddit, I had extensive direct and indirect interaction with people named Newhouse, and I quickly learned that they're the only ones in suits who actually get it. The Newhouse family make for great reddit ownership... as long as they keep it as far as possible from people like this.

Executive summary: Spinning off reddit is a great idea, but selling it is the last thing you should do. No; keep reddit, and find some sucker to unload the rest of Conde Nast on.