Comments on: Mountain Biking Madness

By: Chemical Erik

Chemical Erik — Tue, 23 Oct 2007 02:27:34 +0000

Jordo - While interesting to me, I think any continued statistic discussions will turn away most of the Steve Brown audience.

I'm not odd! I'm not even an integer!

By: Jordo

Jordo — Tue, 23 Oct 2007 01:03:16 +0000

Huh, that wasn't me. That was an impostor.

Just kidding. I just forgot to change my moniker on my home PC. LOL. (Laughing Obnoxiously Loud? Heh)

By: Jordan (w.m.s.n.b.s)

Jordan (w.m.s.n.b.s) — Tue, 23 Oct 2007 00:58:31 +0000

Yay! That's right, chem. Its a principle based on Bayesian statistics. It is completely non-intuitive. A lot of people thought when asked this question that because you are ultimately choosing between only two doors the probability would be 1 out of 2 or 50% in favor of the switch. Ths is not the case. Bayse showed that probability changes when you introduce previous conditions into the math. Consider this; what are the chances that the exit is in one of the other two doors (lets call this set A)? 2 out of 3, right? Well, since the rule states that the exit is not removed when the door is taken away, even thought set A is reduced to one door, the probability does not change. Another concept based on Baysesian statistics is the Carter catastrophy which states that because the human populaion grows exponentially you are more likely to be born toward the end of human existance than being born toward the beginning. In fact, it it theorized that you have a 90% chance of being born in the last 30% of the existance of man. It is non-intuitive, but the math is sound. Note that this assumes that the growth of the population is constnt. It is not.

By: Chemical Erik

Chemical Erik — Mon, 22 Oct 2007 18:53:16 +0000

Make that
"If you switch doors, your chances are 2 out 3" that you find the exit.

By: Chemical Erik

Chemical Erik — Mon, 22 Oct 2007 18:36:19 +0000

Jordo - If you choose the door you touched, the odd's are 2 out of 3 time you're lion food. If you switch doors, your chances are 2 out 3.

This is a famous question from the "Ask Marilyn" column by Marilyn Savant in Parade Magazine. It created an uproar amonst PhD statisticians. Check out her website for a good explaination:
http://www.marilynvossavant.com/articles/gameshow.html

By: Jordo

Jordo — Mon, 22 Oct 2007 14:45:12 +0000

Cool, yo, that's like a video game. I think I'll watch it again.

By: Jordo

Jordo — Mon, 22 Oct 2007 14:44:45 +0000

I have a riddle for you….
Consider that you are in a room there are three doors in front of you. Behind two of them lions wait. Behind the third is the exit. You can't determine which door is which by listening for the lions because the doors are sound proof. In fact, there is no indication which door is which. Assume that if you choose one of the doors without opening it (touch the knob or something), one of the other doors, one that has a lion behind it, will disappear. Now assume that you select a door at random (again without openning it). One of the lion doors disappears (you are told that it is a door with a lion behind it) leaving two doors, your door and the other option. What is the chance that picking the other door will mean your freedom?

By: greg from canada

greg from canada — Mon, 22 Oct 2007 14:12:49 +0000

Erik, I never knew you could bike like that!

By: chris g

chris g — Mon, 22 Oct 2007 13:39:38 +0000

omg! thats sick. im linking this up to my blog. thanks.