Estimation is a crucial element of software project

planning. Unfortunately, there are inherent limitations in

the ability to estimate projects accurately due to the

inherent uncertainties in software projects.

In 1968, Alfred Pietrasanta of IBM System Research

Institute wrote, "Anyone who expects a quick and easy

solution to the multifaceted problem of resource estimation

is going to be disappointed." Thirty years later, Lionel

Briand and his colleagues observed that "Despite the large

number of cost factors collected and the rigorous data

collection, a lot of uncertainty in the estimates can be

observed" (Briand et al., "An Assessment and Comparison of

Common Software Cost Estimation Methods," Proc. Int'l Conf.

Software Eng., [ICSE], IEEE 1999, pp. 313322). It's now

2006, and we still have problems with estimation.