Software Testing - CMMI

How is appraisal done in CMMI?
SCAMPI stands for Standard CMMI Appraisal Method for Process Improvement. SCAMPI is an assessment process used to get CMMI certified for an organization.

There are three classes of CMMI appraisal methods: Class A, Class B, and Class C. Class A is the most aggressive, while Class B is less aggressive, and Class C is the least aggressive.
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Let's discuss these appraisal methods in more detail.

Class A: This is the only method that can provide a rating and get you a CMMI certificate. It requires all three sources of data instruments, interviews, and documents.

Class B: This class requires only two sources of data (interviews and either documents or instruments). But please note you do not get rated with Class B appraisals. Class B is just a warm-up to see if an organization is ready for Class A. With less verification the appraisal takes less time. In this class data sufficiency and draft presentations are optional.

Class C: This class requires only one source of data (interviews, instruments, or documents). Team consensus, validation, observation, data sufficiency, and draft presentation are optional.

Which appraisal method class is best?
Normally, organizations use a mix of the classes to achieve process improvement. The following are some of the strategies which an organization uses:

First Strategy: Use Class B to initiate a process improvement plan, after that apply Class C to check readiness for Class B or Class A. The following diagram shows this strategy.
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Second Strategy: Class C appraisal is used on a subset of an organization. From this we get an aggregation of weakness across the organization. From this we can prepare a process improvement plan. We can then apply a Class B appraisal to see if we are ready for Class A appraisal. The following diagram shows the strategy.
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Third Strategy: Class A is used to initiate an organization level process. The process improvement plan is based on an identified weakness. Class B appraisal should be performed after six months to see the readiness for the second Class A appraisal rating. The following diagram shows this strategy.
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What different sources are needed to verify authenticity for CMMI implementation?
There are three different sources from which an appraiser can verify that an organization followed the process or not.
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Instruments: An instrument is a survey or questionnaire provided to the organization, project, or individuals before starting the assessment so that beforehand the appraiser knows some basic details of the project.

Interview: An interview is a formal meeting between one or more members of the organization in which they are asked some questions and the appraiser makes some judgments based on those interviews. During the interview the member represents some process area or role which he performs. For instance, the appraiser may interview a tester or programmer asking him indirectly what metrics he has submitted to his project manager. By this the appraiser gets a fair idea of CMMI implementation in that organization.

Documents: A document is a written work or product which serves as evidence that a process is followed. It can be hard copy, Word document, email, or any type of written official proof.

The following figure is the pictorial view of the sources used to verify how compliant the organization is with CMMI.

Which model should we use and under what scenarios?
Staging defines an organization process implementation sequence. So staging is a sequence of targeted process areas that describe a path of process improvement the organization will take. For instance, you cannot do your project planning (Level 2) if you have not done requirements management (Level 2). While in the continuous model you select certain process areas even if they're linked with other process areas and mature there.

So when your organization should only concentrate on specific process areas you will likely go for the continuous model. But if you want your organization to have a specific plan and to achieve not only the specific process but also any interlinked process within that process area you should go for the continuous model.