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Birthday Grapher - 1.2

discover the birthday paradox

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All Time:	(5.0)
Version 1.2:	(5.0)
Selected Version:	1.2
Release Date:	2005-12-21
License:	Freeware
Downloads (version 1.2):	874
Downloads (all versions):	4,202

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Product Description:

Like many people, when I was first introduced probability's infamous "Birthday Paradox" I was in strong disbelief. I saw the formula and accepted it, but never really got it. Recently I decided to convince myself of the validity of the paradox through the creation of a simple computer program. What this program does is takes a test-pool (or what I call a "room") and for each "person" in the "room" picks a number from 1 to 365. Then it checks to see if there are any duplicate numbers and returns "1" if there are and "0" if there aren't. Then it repeats this process a user specified number of times until it finally averages all of the ones and zeros together to produce a probability. For the fun of it, I decided to have the program graph whole ranges of room-sizes to show the really unintuitive behavior of this problem. This program doesn't do much, but it does what it says it will pretty well. It's worth taking a look at.

What's new in this version:

In response to a user request, I made the number of days per year user-determinable.

Operating System Requirements:

This product is designed to run on the following operating systems:

Mac OS X 10.4 PPC
Mac OS X 10.3.9
Mac OS X 10.3

Additional Requirements:

Mac OS X 10.3 or later but no guarantees are made. Performance decreases as the number of trials increases.

Feedback Summary:

Version 1.2:
Overall Rating:	(5.0)	Features:	(3.0)	Support:	(3.0)
Ease of Use:	(5.0)	Quality / Stability:	(3.0)	Price:	(5.0)

Key to Types of Feedback:

Reviews Reviews Troubleshooting Usage Tips Developer Notes Commentary Featured Reviews

Nice basis for Monte Carlo simulation... - Version: 1.2, 12/22/2005 01:41AM PST

GerryA

Each year I bet my student class that two students will share a birthday. Nice to see this example worked through using something very much like a Monte Carlo simulation! Of course, it would be fun, if possible, to add parameters such as the probability distribution for the initial assignment of 'birthdays' to each member of the room (birthdays neither have a uniform (flat) nor normal distribution, but depend on the seasons, vacation times, and even power outages and major televised sports events!). This would then be a VERY useful example of Monte Carlo simulation. But like zonkerz hinted in another review, a 'stop' button would be useful to avoid force-quit when setting the number of trials too high for whichever machine you're running on! Nice job! Thanks!

fun - Version: 1.1, 12/21/2005 06:07PM PST

(1 of 1 users found this comment useful)

zonkerz

This is a fun little app. I usually do the birthday paradox in class if I have more than 20 students. It's amazing how often it works out. Once in a class of about 20 people I had three people with the same birthday. I wonder what the probability of this is.
The only problem I had was that I found it hard to get out of the program while it was calculating and graphing. Had to do a force quit.
Anyhow, thanks to the author for dreaming this up and providing it free.

Jack