[EL] McDonald study, birthdate distribution in real voter list

[Michael McDonald]

As stated in the article, we used exact birth date: day, month, and year.
Ignoring year, you only need 23 people to have a 50% probability of a match
that two people share the same birthday. For 57 people, the probability is
nearly 100%, which is why this makes a good class demonstration in a
moderately large statistics class. 

============
Dr. Michael P. McDonald
Associate Professor, George Mason University
Non-Resident Senior Fellow, Brookings Institution

                             Mailing address:
(o) 703-993-4191             George Mason University
(f) 703-993-1399             Dept. of Public and International Affairs
mmcdon at gmu.edu               4400 University Drive - 3F4
http://elections.gmu.edu     Fairfax, VA 22030-4444


-----Original Message-----
From: law-election-bounces at department-lists.uci.edu
[mailto:law-election-bounces at department-lists.uci.edu] On Behalf Of Bev
Harris
Sent: Sunday, September 11, 2011 2:29 PM
To: law-election at department-lists.uci.edu
Subject: Re: [EL] McDonald study, birthdate distribution in real voter list

> if you've got 180 voting-age people in a "room", there's a 50% chance that
two
of them will share the same date of birth.

Omitting the year, right? That's a huge omission and it changes everything.

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