Friday, April 11, 2008

The Monty Hall Problem

The New York Times has a fascinating "game" to play over at their site. Here's background on it:

The economist, M. Keith Chen, has challenged research into cognitive dissonance, including the 1956 experiment that first identified a remarkable ability of people to rationalize their choices. Dr. Chen says that choice rationalization could still turn out to be a real phenomenon, but he maintains that there’s a fatal flaw in the classic 1956 experiment and hundreds of similar ones. He says researchers have fallen for a version of what mathematicians call the Monty Hall Problem, in honor of the host of the old television show, “Let’s Make a Deal.”

Here’s how Monty’s deal works, in the math problem, anyway. (On the real show it was a bit messier.) He shows you three closed doors, with a car behind one and a goat behind each of the others. If you open the one with the car, you win it. You start by picking a door, but before it’s opened Monty will always open another door to reveal a goat. Then he’ll let you open either remaining door.

Suppose you start by picking Door 1, and Monty opens Door 3 to reveal a goat. Now what should you do? Stick with Door 1 or switch to Door 2?

Try it here. There are other links at the New York Times in this series and feel free to click away. But watch out for that game - it might replace Solitaire.


Václav Patrik Šulik said...

Two attempts, two cars.

I quit while I'm ahead.

Kevin said...


Thank you for pointing this out, BB! I've forward it to my econ friend.