Difference between measurement objectives and process performance objectives

CMMI uses following terms while talking about measurements:

1. Identified information needs and objectives at organization level (MA)
2. Measurement objectives derived from such information needs and objectives (MA/SP 1.1)
3. Quality and Process Performance Objectives (OPP/SG1)

I want to investigate finer differences between the later two. Are they more or less the same? If not, what are the finer differences?

Your first two questions deal with Measurement and Analysis (MA) which is a Maturity Level 2 Process Area (PA). Your third question is about OPP which is a Maturity Level 4 PA.
MA is a support PA that applies to ALL PAs in the CMMI. Its focus is defining measures and indicators that help answer or address a specific information need. An information need can be articulated using the following format:

<someone> needs to know <what information> in order to make <what decision>.

For example, an issue facing the Project Manager may be that Project Plans are inaccurate causing project teams to routinely miss milestones and deliveries.
Therefore the information need would be: The Project Manager needs to evaluate the schedule, progress, and dependencies of key development activities and events in order to determine necessary corrective actions.
Then the measurement concept or strategy for addressing this information need would be: At the end of each week the Project Manager collects estimates to complete the work for each current task and enters the data into the schedule. The Project Manager and team review progress to determine the necessary corrective actions and modify the Project Plan as needed each Monday morning.
Now it becomes very easy to determine the base and derived measures that support the measurement concept.

So these concepts (information need, measurement concept, and measures) are interrelated concepts that help define what data to collect and analyze to help answer a question.

The Quality and Process Performance Objectives (QPPOs) are entirely different from the measurement concept. The QPPOs are objectives set by the organization based on the organization’s business objectives, past performance of projects, and are constrained by the inherent variability or natural bounds of the process. Now, in order to determine the measures that the organization will use to support the QPPOs, the organization should follow the MA process of articulating the information need, defining the measurement concept, and determining the measures.

ML 2/ML 3 Measurement Objectives

For a Maturity Level 3 organization , is it acceptable if the organization sets its process performance objectives qualitatively? For example reduce testing cycle time , improve productivity, etc. and in OPF SG1, one of sub-practices states that process performance objectives may be expressed either quantitatively or qualitatively. Also would you please explain this clarification linking to ML2- MA - SP 1.1 - Establish measurement objective?

These are good questions, but the best way to receive a decent understanding of the concepts it to attend the SEI’s Introduction to the CMMI class. Intro to CMMI course description Brief answers, such as mine in this blog, will probably only raise more questions that would be better addressed in a classroom setting.

1. Only for High Maturity organizations (ML 4 and 5) is there an expectation for quantitatively setting process performance objectives. It is acceptable at ML 3 for qualitative objectives. But to fully understand this distinction you really require a good discussion on the expectations for each Maturity Level, which you would receive in the Intro to CMMI class.
   
2. A measurement objective is different from a process performance objective. The measurement objectives are the purposes for which measurement and analysis is performed and also specify what kinds of actions may be taken as a result of data analyses. In order to determine the measurement objectives, you first have to describe the information needs. An information need is an insight necessary to manage objectives, goals, issues, risks, and problems. The measurement objective is derived from the information need and it is a statement about what should be measured in order to satisfy the information need. For example, the project manager or other decision maker concerned with allocating budget and associated resources to a task may believe that productivity is related to the type of task being performed. Increasing productivity is then the measurement objective that addresses the defined information need. Determining productivity then requires that entities such as the product and the process be measured. There are many ways that productivity can be computed, but the measurement objective is unaffected by the different methods.

To fully understand these concepts you should take a class on Measurement and Analysis or Practical Software Measurement. Trying to explain these concepts in a paragraph or two does not do the subject justice.