Research design explained | Empirical evidence activity

Kelley (2004) recommends using the Monty Hall Dilemma (also called the “Let’s Make a Deal” Dilemma) to show that the empirical approach can be superior to relying exclusively on intuition.  If you are unfamiliar with the Monty Hall dilemma made famous by Marilyn vos Savant in her Parade Magazine column), go to any of the following websites:

• http://math.ucr.edu/~jdp/Monty_Hall/Monty_Hall.html

   

• http://www.cut-the-knot.org/hall.shtml

   

• http://www.fortunecity.com/victorian/vangogh/111/9.htm

• http://www.stat.sc.edu/~west/javahtml/LetsMakeaDeal.html

 

 

Kelley reports that students are convinced that changing from their original guess will not increase their chance of winning the prize. He notes that even when he tells students why changing from their original guess improves their odds of winning, most are still unconvinced. To see that changing really does matter, he has the class do a study to determine whether  it is better to stay with one’s original guess or to change.

 

He gives students two copies of a data sheet—one for the “stay” strategy and one for the “switch” strategy. (The data sheets are similar to the one at the end of this file.)  Each student prepares to be the experimenter by using a random number table to select a winning door for each trial. (To help students assign random numbers, you may want to show them "the randomizer" at http://www.randomizer.org. If they need help after getting to the randomizer, you could show them how to fill in the values for the randomizer by showing them this screenshot.) Then, students form pairs. One member of the pair is the experimenter (host) and collects data from the other member (the contestant/participant). After the experimenter/host has run both the “stay” and the “switch”conditions,  the experimenter becomes the participant and the participant becomes the experimenter.

 

If you want to speed things up (the demonstration can take between 10 and 40 minutes), you could have students use only 20 trials in each condition. If you wanted to speed things up even further, you could have students do the task on the web at one of the sites below, all of which offer simulations of the Monty Hall Dilemma:

 

http://www.mredkj.com/javascript/prob_rules.html

 

http://www.cut-the-knot.org/hall.shtml

 

http://www.fortunecity.com/victorian/vangogh/111/9.htm

 

 

http://www.iwaynet.net/~ggwiz/f/3crdmnty.htm  ( three –card instead of three-door)

 

 

 

Strategy (Stay or Switch) _______

 

Trial	Winning door	Contestant’s first choice	Door opened by host	Contestant’s final choice	Contestant’s outcome
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