- Construct a partial implementation of a total system
- Then slowly add increased functionality
- The incremental model prioritizes requirements of the system and then implements them in groups.
- Each subsequent release of the system adds function to the previous release, until all designed functionality has been implemented.
Incremental Model Strengths
- Develop high-risk or major functions first
- Each release delivers an operational product
- Lowers initial delivery cost
- Risk of changing requirements is reduced
Incremental Model Deficiencies
- Requires good planning and design
- Well-defined module interfaces are required
- Total cost of the complete system is more.
When to use the Incremental Model
- Reduce risk by developing in Increments and getting client approvals
- Most of the requirements are known before hand but are expected to develop over several iterations
- A need to get basic functionality to the market early
- On projects which have lengthy development schedules
- On a project with new technology where end results are not completely understood
