Diapositiva 1
Diapositiva 1
Diapositiva 1
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Branch-site models<br />
Allow ω vary among branches. Likelihood ratio test (LRT)<br />
• LRT based on χ 2 can be powerful<br />
2Δl = 2 (l 1-l 2) χ 2 distribution<br />
Alternative model (estimated ω 2>1)<br />
Null model (fixed ω 2=1)<br />
• Power is affected by (i) sequence divergence, (ii) number of lineages, and (iii) strength of positive selection<br />
• The most efficient way to increase power is to add lineages<br />
Anisimova, Bielawski, and Yang, 2001, Mol. Bio. Evol. 18:1585-1592.