Mandatory vs Voluntary Design

One design choice shapes a model more than almost any other: whether participation is mandatory or voluntary. It determines who is in the model, how fair it is, and, crucially, how much its evaluation can be trusted. This lesson covers the trade-off, which ties the policy process directly to the evaluation course.

The two designs

• Voluntary models let organizations choose whether to join. Most CMMI models have been voluntary.
• Mandatory models require participation, usually for providers of a certain type in selected regions. The joint-replacement bundle from the case-studies module was mandatory in chosen markets.

The evidence consequence

This is where the policy choice meets the evaluation course head-on.

Worth remembering: voluntary participation biases evidence through selection. Organizations that opt in tend to be the ones expecting to succeed, so favorable results may reflect who joined rather than what the model did. Mandatory participation removes that self-selection, which is why mandatory-model evaluations are the closest thing CMMI produces to a clean test. The design choice is not just about fairness; it determines whether the model can ever be rigorously proven to work.

The tension

Each design has a real cost, which is why the choice is contested:

Design	Strength	Cost
Voluntary	Politically easier; providers opt in willingly	Selection bias; results hard to trust; may attract only the ready
Mandatory	Cleaner evidence; tests the average provider	Political resistance; forces risk on the unprepared

Mandatory models generate better evidence but face fierce opposition, because they compel organizations, some poorly equipped, to bear risk. Voluntary models are easier to launch but can never fully escape the selection critique. CMMI navigates this tension constantly, and the balance shifts with the political appetite for compelling participation.

Why it matters to a participant

If you are tracking or engaging with a model, whether it is mandatory is a first-order fact. It tells you who will be affected, how strong the eventual evidence will be, and where the political fight will be. A proposed mandatory model will draw intense stakeholder response precisely because participation is not a choice, which makes the comment process (Module 3) especially consequential.

Key takeaways

• Whether a model is mandatory or voluntary is among its most consequential design choices.
• Mandatory participation removes selection bias and yields far stronger evidence, the evaluation course’s lesson applied to design.
• The choice is a genuine tension: mandatory models produce better evidence but face political resistance, while voluntary models are easier but never escape the selection critique.