[Ronnie73]

Interesting question. As far as regular "single" type backs like Tolstoi, Polar Bear, EPDG etc.. I don't really have a formula to determine ungraded cards. I tend to compare population numbers with other cards with the same back and from the same print group to get an idea of whats more rare.

As far as the Sweet Caporal Factory 25's. Since they only started keeping track of them a few years ago, I use a ratio of population. I look at PSA's numbers for the same card for Factory 25 and 30. If theres 2 for Factory 25 and 20 for Factory 30, then I know it's 1 Factory 25 for every 10 Factory 30's graded. So if SGC graded 50 Sweet Caporal's from 1910 (350 Subjects), then I guess 5 of those would be Factory 25's. Then I just add up all the numbers. Don't forget to subtract the number of Factory 25 and 30's graded from the PSA number total for that card and then use the same ratio to determine the PSA number for pre Factory Number graded cards.

Be careful using population numbers of HOF's to get full population totals. More HOF's are graded than non HOF's so your 4x or 5x would be different for HOF cards. Then you also have to factor print runs. The 6 Super Prints would have the most cards in the population overall.