The staged model has groups of Process Areas which are divided into 5 Levels. Staged models in CMMI focus on process improvement using stages or Maturity Levels. In the staged representation each Process Area has one Specific Goal. Achieving a Goal would mean improvement in control and planning of the tasks associated with the process. The CMMI staged representation has 5 Maturity Levels.
In the staged representation, summary components are the Maturity Levels. Every Maturity Level has Process Areas, with their Goals and Practices. Practices are categorised by common features:
Commitment to perform
Ability to perform
Below is a diagram showing the structure of the staged CMMI model.
Compare the stage representation diagram with the continuous representation diagram below:
In the continuous representation, Process Areas are the summary components. Every Process Area has Specific Goals that are implemented using best practices. Also included are Generic Goals and Generic Practices to achieve them. The individual Process Areas refer to Specific Goals and Practices whereas the generic ones apply to multiple goals.
In CMMI continuous representation models there are six capability levels which are designated by the digits from 0 to 5:
Capability Level 0: Not performed (or Incomplete) At this Level processes are not performed fully or partially. One or more Specific Goals of the Process Area would not be satisfied. Generic Goals do not exist for this level.
Capability Level 1: Performed At this Level the Specific Practices are all performed either fully or partially. Stable or non-met specific objectives such as quality, cost and schedule may not be performed well, but the work done is useful. Something is being done but it cannot be proven to be particularly effective.
Capability Level 2: Managed At this Level processes are planned, performed, monitored and controlled for individual projects or groups (or could be stand-alone for achieving a given need). Both the model objectives for the process and other related objectives like cost, schedule and quality are managed. The things that are to be managed are managed actively. There are metrics which are collected and applied consistently to aid management decisions.
Capability Level 3: Defined At this Level processes are characterised as “well defined”. The processes are managed and adapted for the standards of the organisation in accord with the documented tailoring guidelines. Work products, measures and other process-related improvement information contribute to the achievement.
Capability Level 4: Quantitatively Managed At this Level processes are properly controlled using statistical and other quantitative techniques. Quality and process performance are established and used as the major criteria in process management. The quality of process performance is estimated in statistical terms. Quality is managed throughout the process life cycle.
Capability Level 5: Optimising At this Level processes are quantitatively managed and improved upon based on understanding inherent variations. The focus is on continually improving the performance of the process by incremental and innovative changes.