If you really think your employee's performance is on a bell curve, you should fire your HR department.

A recent kerfuffle over in Yahoo Land has got me thinking about the mis-application of statistics.

http://allthingsd.com/20131108/because-marissa-said-so-yahoos-bristle-at-mayers-new-qpr-ranking-system-and-silent-layoffs/

The assumption is that employee performance follows a bell curve. But you only get a bell curve in your sample of a larger population if your sample is random and the larger population is also a bell curve.

What this means is that if your employee's performance truly follows a bell curve, then you should fire your HR department and completely replace all those expensive people with a random process that just picks a resume out of the hat. Frankly, I suspect you'd be hard pressed to tell the difference in most organizations.