transition/transversion calc?

Joe Felsenstein joe at GENETICS.WASHINGTON.EDU
Mon Aug 15 17:32:11 EST 1994


Steve Hardies wrote (as part of a longer post):

>     Now my question is, what happens if you merge divergent sequences
> with saturated transitions into data with more closely related sequences?
> Will the liklihood curve for Ts/Tv broaden over what it would have been
> with the closely related sequences alone?  That is, will you convert
> uncertainty about the divergent branch lengths into uncertainty about
> the global Ts/Tv?

I would think that it will not broaden.  If you add to data that implies a
given amount of uncertainty about Ts/Tv ratio some more distant sequences that
would be compatible with any Ts/Tv ratio, surely the uncertainty gets no worse,
as in effect one is adding irrelevant data, and the likelihood method
knows that.

-----
Joe Felsenstein, Dept. of Genetics, Univ. of Washington, Seattle, WA 98195
 Internet:         joe at genetics.washington.edu     (IP No. 128.95.12.41)



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