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 |
Read more about this topic: Software Development Effort Estimation
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