I rated myself at 7.3 - my doctor didn't supply the rating.

I think people can tell when they're feeling 90% (more or less), and whether or not we're still experiencing symptoms like headaches, tinnitus, dizziness, etc.

However, a more nuanced and objective assessment of one's cognitive abilities and balance and other physical skills, might require a neuropsych, BESS, IMPACT, or other concussion-related test.

In other words, PCS seems to involve both a subjective element (how the patient feels) and an objective element (how he or she performs on standardized tests and/or tasks).