I used to be one of the three worst software development estimators in the world. Okay, I was probably *the* worst. I could not estimate the time or cost of a software development project to save my life. Then I learned about this thing called Function Points, and Function Point Analysis, and other common sense things, like the Law of Averages, and my estimating life is much, much better. I might even challenge someone to a contest one of these days.
