Question for Front/Back collectors

[Rascal1010]

Just have a general question for front/Back combination collectors on determining rough idea of how many examples of a card are in the hobby. I know the PSA population reports are not accurate, nor is SGC, and SGC makes it difficult by not noting factory differences in their population report. I have gone through Scott Reader's % of population by backs in respect to the overall production, and his data does correspond with fairly close with data that I have pulled from PSA's population report for distribution %, there are always a few outliers. My question is there a factor that anyone uses based off PSA's population to help determine a rough idea of how many of that front back combination are actually in the hobby, or do you have another way of calculating rough estimates on total populations?

Example #1 - Rube Kroh Sweet Caporal 350/25 - PSA shows a pop. of 2, I know there are more than 2 in the hobby, because I own one in an SGC holder. I know this card is also a very low population card, so wondering how many really do exist yet. My guess is PSA's report could be taken by 4X or 5X and it would be close to the total number in the hobby, between cards in SGC, BVG & raw that aren't accounted for in PSA's population report, but am hoping for some feedback from some other collectors on what they have experienced. My 4X - 5X may be way off on what's really out in the real world, it is just my estimate.

Example # 2 - Evers (Chicago on Shirt) Sweet Caporal 350/30 PSA pop. 79. By my calculation using a 4X factor that would mean there are roughly 316 total of this front back combination in the hobby.

Hopefully some other members have a better way of determining an estimate of how many of a front/back combination really exist. Any feedback is welcome!