What is Incremental Model?

Definition - What is incremental process model ?

The process model that delivers a series of releases called as increments, that provide progressively more functionality to the user as each increment is released is called incremental process model. The incremental model contains the same elements of waterfall model applied in an iterative fashion. This model applies linear sequences and releases increments as calendar time progresses.

Working - How incremental process model works?

Incremental Process Model

The first increment in this model is called as a core product. In the first increment only the basic requirements are implemented and many optional features are not. This core product is used by customer or user to get the feedback about the product. When the feedback is collected a plan is made to make modifications in the first increment, the plan is devised accordingly to better meet the needs of customer and to deliver some additional features and functions in the next increment. This process is repeated after the delivery of every increment until all the needs are satisfied, that is until complete product is produced.

The incremental process model is iterative in nature like prototyping other evolutionary approaches. But incremental model delivers an operational product with each increment released unlike prototyping. Early increments are striped down versions of the final product. These versions provide the user capability to use and to evaluate them.

Uses - When to use incremental process model?

When there is a lack of development team for implementation of complete product within given business deadline incremental model is used. First few increments can be implemented with small group of people. If the core product is accepted by the user then required staff can be added to develop next increments.

Example of Incremental process model

Suppose incremental model is used to develop a an editor. Then in the first increment only the basic requirements like file management, document creation and editing can be implemented. In the second increment spelling and grammar checking feature can be added. In the third increment advanced layout functionalities can be added. In this fifth increment a functionality to handle syntax highlighting programming languages can be added and in the sixth increment the editor can suggest words or coding statements before user types the full statement. This is how incremental model works.

Advantages of incremental model

  1. Results can be seen early and periodically.
  2. We can measure progress periodically.
  3. One can change the scope of project with minimum costs.
  4. Operational product is delivered with every increment released.

Disadvantages of incremental model

  1. As it is made in increments total cost is higher than waterfall model.
  2. It needs good design and planning.
  3. It needs perfect definition of the whole system before incremental model is used.