I used BLAST on a sequence, the top hit I found had an E-value of 2e-48, however, the identity percentage was only 54%. Looking at the identity percentage I wouldn't say the match is significant but the E-value is very low, so considering that could I conclude that the significance of the similarity is high?
E-value = 0, means the good and e-value lower would indicate that the hit by chance.
In such case, other parameters like percentage identity, query coverage should also be taken into consideration.
And of course common sense of "does the hit really is similar to query"
Just looking at the e-value alone is not so conclusive.
E-value describes the number of hits that would occur by chance. An E-value around zero is preferable. The lower the better.
The BLAST E-value is the number of expected hits of similar quality (score) that could be found just by chance. E-value of 10 means that up to 10 hits can be expected to be found just by chance, given the same size of a random database.
- Badges
- Science topic
- Similar topics
- Books