Judge

The estimation is done by cognitive judgment and is considered as an evaluation of evidence in the formation of making a decision. It is commonly used for software cost estimation but is also known as the least accurate method for estimation.

Description

The judgment estimation is often used in Software Engineering. refers to the judgment method as the least accurate means of estimation. Estimations are only accurate if they can be tied to conrete facts. It can be used for Size, Effort, Schedule and Feature Estimation. Judgment shall be used to make rough estimations only and in any case be accompanied by other estimation methods. Historical data combined with computions can easly undermine judgment-bases estimates. McConnel also recommends to not use judgment to verify or tweak computed estimates. Judgment usually degrades the estimate's accuracy.  Judgment estimates tend to be over-optimistic. Factors like wishful thinking, planning fallacy and cognitive dissonance are influencing the personal judgement. This shall be considered for all methods where personal judgment is involved.

Example

When McConnel wrote the book '"Code Complete"' he had a team that inspected the first edition which consists of about 900 pages. The first inspection showed that the inspection rate per page was about 3 minutes. McConnel realized that this would mean 45 hours of work, so he commented that he, in his judgment, thought that the minutes per page will speed up for the next meetings to 2 or 2.5 minutes. Luckily the project manager didn't approve because as it turned out the average inspection was 3 minutes per page.