[Bioperl-l] What does Expect(2) mean in a blast result?

Dave Messina David.Messina at sbc.su.se
Sat Nov 10 06:04:25 EST 2007

Hi Amir,

I don't have my BLAST book handy, and my memory is a little fuzzy, but I
think the Expect(2) you're seeing is the E-value based on both HSPs
combined. And I think this is why you see the same Expect value for both --
because it is shared between them (which sounds like what you wanted).

Again, this is just from memory, but I think this is an option that has to
be turned on rather than something which Blast decides to do on its own.

I don't know whether BioPerl reports this or not. Would you mind e-mailing
me a entire BLAST report as a sample? When I have some time I'd like to play
around with this a bit.


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