I have been told that if an organization has to go for CMMI ML 5 the organization has to address all of the sub-practices even though they are informative material and if the company is only going for ML 3, then they can apply appropriate sub-practices. Is this true?
Please allow me to try to explain the model. There are at least two ways to look at the CMMI: 1) implementing the model and 2) appraising the organization against the model.
In addition, there are three CMMI components: Required, Expected, and Informative. These components only have meaning when you are talking about appraisals. The Required components are the Specific and Generic Goals, the Expected components are the Specific and Generic Practices, and everything else is an Informative Component.
When you are implementing the model, you should not be concerned about differentiating between the different types of components. From Chapter Two of the CMMI-ACQ (and this statement applies to ALL CMMI constellations): “All model components are important because the informative material helps you to understand the expected and required material. It is best to take these model components as a whole. If you understand all three types of material, you can then understand all the pieces and how they fit together to form a framework that can benefit your organization.”
When the organization is being appraised against the CMMI in a formal SCAMPI A appraisal, the organization will only be appraised against the Required and Expected components, regardless of the Maturity Level. However, the appraisal team may be evaluating the evidence and perhaps asking questions in the interview sessions at the sub-practice level just to gain a better understanding of how the organization is addressing each of the Required and Expected components. The organization will not be penalized if it is not performing one or more sub-practices. The appraisal team will be identifying and documenting weaknesses with the organization’s implementation of the goals and practices.
Because there has been a misunderstanding of what High Maturity means (ML 4 and ML 5), the SEI has been emphasizing that the proper implementation of the goals and practices for OPP, QPM, OID, and CAR means reading, understanding, and implementing the types of activities described in the Informative material. So, for a ML 4 or ML 5 SCAMPI, the organization will not be evaluated against the OPP. QPM, OID, and CAR sub-practices, but weaknesses will be noted at the goal and practice level if the organization has not properly implemented these Process Areas to meet the intent, which is gained by understanding the Informative material.