That's my back-of-the-envelope rule of thumb in a nutshell. (Who doesn't love idioms?)
Also, one doesn't have to do a full census to get a good picture of the whole. A sample of 30 or so would get a pretty good estimate of what those ratios should be. (Picking every 17th card might be better than doing all the A name cards because it's less likely to encounter clustering.) It's even possible to get a good error range with that few.
Quote:
Originally Posted by RCFire82
James,
Quick rule of thumb I use when looking at psa's pop. report on Sweet Caporals is to use ratios. For example on the Abbaticchio (blue sleeves) above:
Let's say total Sweet Caporals graded is 160 (which is close) and 80 (or exactly half) have been identified with Factory numbers. I would say it's safe to say each Factory graded total, 460 25 (10 total), 460 30 (58 total), and 460 op (12 total) can be multiplied by 2. So one would expect to see an additional 10 460 fac 25's, 58 more 460 fac 30's, and 24 total 460 over prints when examining the 80 earlier non Factory labeled psa graded cards.
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Edited to add:
Just following the rules, even though I love the pretty tables.