Posted By:
Eric BrehmIf I have a set on the registry, and I get 8 points for a PSA 8, 8.5 points for a PSA 8.5, and 9 points for a PSA 9, then an 8.5 card should be halfway between an 8 and a 9, quality-wise (not necessarily value-wise, of course). If only 15% of existing PSA 8 cards are considered good enough to get a half-grade bump, and I have one of those, I should get 8.85 points for it!
One other thing to keep in mind though, is that the percentage of cards that do receive the half-grade bumps will be skewed somewhat by the fact that people will tend to submit stronger cards within each grade (i.e. that have a higher likelihood of being re-graded).