Merging blast output files

Gary Williams gwilliam at hgmp.mrc.ac.uk
Fri Apr 28 07:21:12 EST 2000


In article <kjpurbhb01.fsf at alpha0.bioch.virginia.edu>,
William R. Pearson <wrp at alpha0.bioch.virginia.edu> wrote:
>
>
>Steven Smith <ssmith at itis.com> writes:
>
>> You do need to be careful when comparing e-values.  They take into account
>> the size of the database searched.  The e-value means "I expect to find X
>> hits when searching this sequence with a database of size Y." So e-values
>> are comparable when Y's match.
>
>Although "bit" scores are not so intuitive, Steve Smith's post
>highlights their advantage over E()-values.  Both blast2 and fasta33
>"bit" scores attempt to summarize the same information, which is
>database size and query size independent.

Most of our software that parses the blast output uses and stores the E-value.

Is there a formula for converting bit-score, database size into an E-value?

Gary





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