Barry W Boehm and Richard E Fairley's article on Software Estimation Perspectives contains a one page essay by Grant illustrating some of the issues when people make estimates.
Measuring software size is important for estimating project resources, schedules and effort, yet it has depended on methods dating back to the 1970s and 1980s. A new free standard method is now emerging which takes account of modern developments.
Charles Symons, who helped develop it, explains.