<\/span><\/h2>\nThe E-value, short for Expected value, is used in sequence database searches, particularly in bioinformatics. It helps assess the statistical significance of sequence similarity matches when searching a database. The E-value represents the number of false positives statistically expected to occur by chance in the search, given the size of the database and the scoring system used.<\/p>\n
Unlike the p-value, which ranges from 0 to 1, the E-value can be any positive value. The lower the E-value, the more significant and unlikely the match is to have occurred by chance alone. Therefore, a smaller E-value signifies a more meaningful sequence similarity.<\/p>\n
How is E-value related to the p-value?<\/strong><\/p>\nThe E-value and the p-value are related through a mathematical transformation. The E-value is derived by transforming the p-value, making it easier to interpret in sequence database searches. However, it’s important to note that the E-value represents significance in the context of sequence similarity rather than testing hypotheses.<\/p>\n
When comparing E-values and p-values, a smaller E-value corresponds to a smaller p-value, indicating stronger evidence against the null hypothesis. This relationship can be understood as follows:<\/p>\n
<\/p>\n- Smaller E-value = Stronger evidence for sequence similarity <\/li>\n
<\/p>\n
- Smaller p-value = Stronger evidence against the null hypothesis <\/li>\n
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Therefore, a smaller E-value indicates a more significant match based on sequence similarity, while a smaller p-value suggests stronger evidence against the null hypothesis in hypothesis testing.<\/p>\n