Migration Parity Eval
Also: parity check · equivalence evaluation · pre-cutover validation
Proving the new system produces equivalent results to the old one before you cut over — not after.
Why CCAR-P tests this
The exam checks whether you validate equivalence before cutover, since post-cutover is too late to discover the new path is wrong.
A migration parity eval runs the old and new systems side by side and proves they produce equivalent outcomes on the same inputs — same results, same edge-case handling, same compliance behavior — before any traffic is moved. The non-negotiable is timing: parity eval before cutover.
Running the eval after cutover inverts the point. Once the old path is gone, a parity gap becomes a live incident with a high reversal cost instead of a quiet finding you can fix. Parity is what makes a blue-green flip or a canary ramp safe: the flip is only reversible-in-theory if green was proven equal to blue first.
A credible parity eval names its comparison set, its tolerance for acceptable difference, and its measurement owner — otherwise it risks the "measured the wrong thing" failure, declaring parity on a metric that was never the one that mattered.
Exam trap
Any plan that cuts over first and validates parity afterward is the trap; equivalence must be proven while the old system is still available to compare against.
Commonly confused with
Independent, unofficial study material from Claude Cert Prep. Not affiliated with Anthropic.