Tuesday, May 19, 2009

Monty Hall answer and final clarification

And the answer is..... switch doors. When you chose your door you had a 30 percent probability of choosing the car. After the other door is open and reveals a goat in essence your chosen door has stayed at 30 percent however the other door has picked up the probability from the opened door. As for the random vs. Monty Hall playing the game and knowing what was behind the door, for a single trial it doesn't matter so long as the door that is opened reveals a goat. On multiple trials it is a little different, since you would expect that the door with the car would be revealed a third of the time if it was truly random. The following link explains the problem a little better and also has an applet that will let you run the problem on a single trial, 10 trials, 100 trials and 1000 trials.
www.statisticalmisconceptions.com/MiscAndInvite05c.html
I was playing with it the other day and ran a dozen single trials and got a fifty fifty turn out. The problem really reveals itself over multiple trials (like 50 or more). It also runs on the assumption that the door opened never reveals the true prize. Which brings up another dilemma. Humans are horrible at creating randomness. We just can't do it. So in research, we use computers to generate random numbers. The problem is how can you program a computer to create random numbers, when the computer runs off of a mathematical algorithm that given enough data you could solve for, so is it truly random?

2 comments:

Leah said...

Well imagine that. I was actually right. That NEVER happens!

Meredith and Abe Fish said...

It seems that you explaination is pretty complicated, I found this one which is pretty basic. For this explanation to work consider the car is behind door A, and goats behind doors B, and C. This gives you three scenarios. If you pick door A and then you are shown door C and you switch then you lose. That is one of three scenarios. The other two scenarios you choose doors B or C you are shown the other door with the goat you switch and you win. So two out of the three scenarios if you switch then you. Simple right.