Back in May’s Carnival of the Agilists I referenced a post by Clarke Ching in which he suggests we can learn a lot about variation in a complex process by simply flipping coins. When I tried the simulation a few times with Excel I found, as expected, that heads and tails don’t always occur in equal measure. But that was a pain to do, so I’ve made it easier. I’ve written a little Ruby program that simulates 1000 coin tosses; you can get it from github.
(Disclaimer: The images are SVG. It works fine in Firefox, but if you use IE you may need to install some kind of viewer.)