Software Development Effort Estimation - Estimation Approaches

Estimation Approaches

There are many ways of categorizing estimation approaches, see for example. The top level categories are the following:

  • Expert estimation: The quantification step, i.e., the step where the estimate is produced based on judgmental processes.
  • Formal estimation model: The quantification step is based on mechanical processes, e.g., the use of a formula derived from historical data.
  • Combination-based estimation: The quantification step is based on a judgmental or mechanical combination of estimates from different sources.

Below are examples of estimation approaches within each category.

Estimation approach Category Examples of support of implementation of estimation approach
Analogy-based estimation Formal estimation model ANGEL, Weighted Micro Function Points
WBS-based (bottom up) estimation Expert estimation Project management software, company specific activity templates
Parametric models Formal estimation model COCOMO, SLIM, SEER-SEM
Size-based estimation models Formal estimation model Function Point Analysis, Use Case Analysis, SSU (Software Size Unit), Story points-based estimation in Agile software development
Group estimation Expert estimation Planning poker, Wideband Delphi
Mechanical combination Combination-based estimation Average of an analogy-based and a Work breakdown structure-based effort estimate
Judgmental combination Combination-based estimation Expert judgment based on estimates from a parametric model and group estimation

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