Question

In Shimodaira–Hasegawa Test, The degree of freedom used for the analysis depends on the substitution model used. It relies on the following test formula d = 2(ln LA – ln LB) = 2 ln(LA/LB). Here, is the log likelihood ratio score and ln LA and ln LB are likelihood scores for tree A and tree B, respectively.

(a) True

(b) False

This question was addressed to me during an online exam.

Question is taken from Phylogenetic Tree Evaluation in section Phylogenetic Tree Construction Methods and Programs of Bioinformatics

Answer 1

The correct choice is (a) True

To elaborate: A frequently used statistical test for ML trees is the Shimodaira–Hasegawa (SH) test (likelihood ratio test). It tests the goodness of fit of two competing trees using the χ2 test. For this test, log likelihood scores of two competing trees have to be obtained first.