Tuesday, July 24, 2018

Only a genetics nerd...

... would do a Bayesian on this...
From my 28D3 F4s, (red cherries) none have the gf phenotype.  What are the odds that any are gf/+ and thus might have some gf/gf progeny next year?  Bayesian analysis to the rescue...

The F1 plant was gf/+.  F2 plant 28D was not gf phenotype; therefore it's prior probability of being gf/+ was 2/3.    Four F3 plants were grown last year; none had gf phenotype either.  28D3 was one of these.  What are the odds that 28D3 still could be a gf/+ carrier?


Hypothesis
Assume F3 = carrier
Assume F3 = non-carrier

Prior
4/9 
5/9

Conditional
(prob that all 3 F4s are non-carriers)

27/64




1


joint
0.141
5/9

posterior
(0.141)/(0.141)+(5/9)=0.202



Therefore the posterior probability that the F3 plant,  28D3, was a gf/+ carrier is 0.202.
Given this, the probability that any particular one of the 28D3 F4 plants is also a gf/+ carrier is = 0.202 x 2/3, or ~ 0.135 = 13.5%.    

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