SCAMPI stands for Standard CMMI Appraisal Method for Process Improvement. SCAMPI is an assessment process to get be CMMI certified for a 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.

Figure: - SCAMPI
Let’s discuss all these appraisal methods in more detail.
Class A: - This is the only method that can provide rating and get you a CMMI certificate. It requires all three sources of data instruments, interview and documents.
Class B: - This 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 that if the organization is ready for Class A. With less verification the appraisal takes less time. In this data sufficiency and draft presentation are optional.
Class C: - It requires only one source of data (interview, instruments or documents).Team consensus, validation; observation, data sufficiency, and draft presentation are optional.
Below table shows the characteristic features with proper comparison.

Figure: - Comparison between Class A, B and C