Parametric estimating is a technique that is essential for any project management team and or project management team leader to become comfortable with using, as the use of parametric estimating provides an invaluable service in the course of the project. Parametric estimating refers, primarily, to an estimation technique which utilizes the statistical relationship that exists between a series of historical data and a particular delineated list of other variables. Some examples of these variables include square footage in a contraction project, the number of lines or code that exist in a software application, and other similar variables. This information is them implemented for the purposes of calculating and demonstrating an estimate for the entity of activity parameters. One valuable aspect of parametric estimating is the higher levels of accuracy that can be built into it depending on how sophisticated the original data that was built into the estimate turns out to have been.
This term is defined in the 3rd and the 4th edition of the PMBOK.