Expect value: Difference between revisions
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The Expect Value (E) is the number of hits that a person would expect by chance when searching a database. The lower this value is, the higher the Score (S) of the match is. The closer the E-value gets to zero, the better the match is | The Expect Value (E) is the number of hits that a person would expect by chance when searching a [[database|database]]. The lower this value is, the higher the Score (S) of the match is. The closer the E-value gets to zero, the better the match is | ||
The lower the E-value, or the closer it is to zero, the more "significant" the match is. But another factor that affects the E-value is the length of query. Since shorter ones have a higher chance of occurring in the database, they tend to have a higher E-value | The lower the E-value, or the closer it is to zero, the more "significant" the match is. But another factor that affects the E-value is the length of query. Since shorter ones have a higher chance of occurring in the database, they tend to have a higher E-value <ref>National Library of Medicine, BLAST Frequently Asked Questions [online], available at: &amp;amp;amp;amp;amp;amp;amp;amp;lt;http://www.ncbi.nlm.nih.gov/blast/</ref>. | ||
=== References === | |||
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Revision as of 11:13, 21 October 2013
The Expect Value (E) is the number of hits that a person would expect by chance when searching a database. The lower this value is, the higher the Score (S) of the match is. The closer the E-value gets to zero, the better the match is
The lower the E-value, or the closer it is to zero, the more "significant" the match is. But another factor that affects the E-value is the length of query. Since shorter ones have a higher chance of occurring in the database, they tend to have a higher E-value [1].
References
- ↑ National Library of Medicine, BLAST Frequently Asked Questions [online], available at: &amp;amp;amp;amp;amp;amp;amp;lt;http://www.ncbi.nlm.nih.gov/blast/