Question

Which of the following is true about Expectation Maximization (EM) method?

(a) The log odds scores of the PSSM are modified at the end of the process

(b) The procedure stops prematurely if the scores reach convergence

(c) The final result is not sensitive to the initial alignment

(d) Local optimum is an advantage of EM method

This question was posed to me in class test.

My question is taken from Motif Discovery in Unaligned Sequences in chapter Sequence Alignment of Bioinformatics

Answer 1

Right answer is (b) The procedure stops prematurely if the scores reach convergence

To explain: The final result is sensitive to the initial alignment. The Local optimum is actually a drawback of EM method. It is same as the fact that the procedure stops prematurely if the scores reach convergence.