Khan Academy on a Stick
Simulation providing evidence that (n-1) gives us unbiased estimate
Simulation by KA user tetef showing that dividing by (n-1) gives us an unbiased estimate of population variance. Simulation at: http://www.khanacademy.org/cs/will-it-converge-towards-1/1167579097
The video could not be loaded, either because the server or network failed or because the format is not supported.
If the above player doesn't work, try this direct link.