A general overview of software estimation techniques...

Few things should be kept in mind while the software project planner begins the project:
- how long will it take?
- how much effort is required?
- how many people are involved?
- what resources are required?
- what kind of risk is involved?
The statement of scope helps the planner develop estimates using one or more techniques that fall into two broad categories:
- decomposition
- empirical modeling.

Decomposition techniques require a delineation of major software functions followed by estimates of either:
- the number of lines of code.
- selected values within the information domain.
- number of use cases.
- number of person months required to implement each function.
- number of person months required for each software engineering activity.

Empirical techniques use empirically derived expressions for effort and time to predict these project quantities. Automated tools can be used to implement a specific empirical model.

By comparing and reconciling estimates derived using different techniques, the planner is more likely to derive an accurate estimate. Software project can never be an exact science but it is a combination of good historical data and systematic techniques that helps in improving estimation accuracy.