Since inception of software industry software experts or senior software engineers have
been responsible for estimation of software size and cost. Their experience in contexts directs them to estimate human effort required for completing of a software package. However, their judgment most often is helpful only in the companies they work in, mainly because such a prediction strongly depends on team experience, project complexity, organizational culture, and so on. Clearly, experts’ judgment (experts’ view) is prone to bias and strongly is subject to human error. Nonetheless, for small or medium projects is useful, especially in companies that development teams and project domains did not experience significant changes.