%% Temple university CIS 2033 % A modern Introduction to Probability and Statistics % Chapter 3 - Conditional probability and independence % % Author: Djordje Gligorijevic % email: gligorijevic@temple.edu %% The probability of no coincident birthdays % Use sameBirhtDayProbability.m script for this demonstration. %% Monty Hall problem % % Reference: http://rosettacode.org/wiki/Monty_Hall_problem % % Run random simulations of the Monty Hall game. Show the effects of a % strategy of the contestant always keeping his first guess so it can be % contrasted with the strategy of the contestant always switching his guess. % % Suppose you're on a game show and you're given the choice of three doors. % Behind one door is a car; behind the others, goats. The car and the goats % were placed randomly behind the doors before the show. The rules of the % game show are as follows: After you have chosen a door, the door remains % closed for the time being. The game show host, Monty Hall, who knows what % is behind the doors, now has to open one of the two remaining doors, and % the door he opens must have a goat behind it. If both remaining doors % have goats behind them, he chooses one randomly. After Monty Hall opens % a door with a goat, he will ask you to decide whether you want to stay % with your first choice or to switch to the last remaining door. % Imagine that you chose Door 1 and the host opens Door 3, which has a goat. % He then asks you "Do you want to switch to Door Number 2?" % % Is it to your advantage to change your choice? (Krauss and Wang 2003:10) % Note that the player may initially choose any of the three doors % (not just Door 1), that the host opens a different door revealing a goat % (not necessarily Door 3), and that he gives the player a second choice % between the two remaining unopened doors. % % Simulate at least a thousand games using three doors for each strategy % and show the results in such a way as to make it easy to compare the % effects of each strategy. numDoors = 3; numSimulations = 1000; [swithcWinPercentage,stayWinPercentage] = montyHall(numDoors,numSimulations); %% Monty Hall problem - code 2 montyHall2(100,3,0)