Statistics and the 66% possibilities....

[ Follow Ups ] [ Post Followup ] [ The Rat Snake Forum ]

Posted by chrish on August 06, 2002 at 10:39:41:

In Reply to: Re: trans pecos? posted by mike17l on August 06, 2002 at 02:53:54:

Given that the Barker's offered a pair of yearlings last year for $1000 each which were 100% guaranteed heterozygous, I wouldn't pay more than $200-300 for a 66% possible het (You have a 1/3 chance that you are just buying an overpriced normal TPR - which sell for between $50 and $75 normally).

The problem with a 66% possible het is that it could take years to prove whether it is actually het due to the small clutch size of these snakes.

Imagine crossing this to a normal snake and producing 6 normal looking babies (each of which now has a .50 x .66 or 33% chance of being het). Then you have to raise and breed these and hope that you can pair two of the possible hets (your chances are now 1/9 that you can pick two hets if there are any) and they breed. Now you have a 1/4 chance of producing an albino snake and finally proving your original. (Your total probability of producing an albino baby from your original adult is now 1/36).

Suppose you don't get an albino in your first litter of F2s. Does that mean you don't have the gene? Of course not. You may have paired two babies that weren't het (only half of them would be if your original snake was) or you may have just not gotten lucky enough to get the 25% albinos you were expecting. How would you know? Try, try again.

Now what if you decide to buy two of the original 66% hets. Now you have a 2/3 x 2/3 x 1/4 = 1/9 chance of producing an albino snake in the F1 clutch. But again, if you don't, you don't know that you don't have two animals with the gene, you just know you didn't hit that time. So you could end up breeding for several years before you find out that you bought overpriced normals. And by this point, the price of albinos will have dropped.

I know we all read the "I got lucky" posts where someone gets a pair of 66%s and they produce albinos in their first year. But remember, the other 8/9 people who don't get any albinos don't post celebrating their failure to beat the odds.

Follow Ups:

snake is from VPI mike17l 08/06/02 (4)
- Another question... chrish 08/06/02 (3)
  - Re: Another question... mike17L 08/06/02 (2)
    - Sounds like a good deal. Hope it turns out to be het! /np chrish 08/06/02 (1)
      - i got it for 55 mike17L 08/06/02 (0)