What is e value? - Bioinformatics and Biostatistics (2024)

FAQs

What is the e-value in bioinformatics? ›

Essentially, the E value describes the random background noise. For example, an E value of 1 assigned to an alignment means that in a database of the same size one expects to see 1 match with a similar score, or higher, simply by chance. The lower the E-value the more “significant” the match is.

The E-value provides a value, measured on the ratio scale, of how strongly an unmeasured confounder must be associated with both treatment and outcome to negate the observed treatment-outcome association.

The E-value is the expectation value that indicates the number of alignments with a score≥S that one can expect to find by chance in a database of size N. Hence, the E-value is dependent on the database size and the query length. The closer the E-value to 0, the better is the alignment.

The E-value of 0.0 indicate the number of alignments with scores equivalent to or greater than that are expected to occur in a database by chance therefore the lower the E-value the more significant the score hence a better quality of the alignment blast search.

Euler's Number 'e' is a numerical constant used in mathematical calculations. The value of e is 2.718281828459045…so on. Just like pi(π), e is also an irrational number. It is described basically under logarithm concepts.

P-value: Probability that an event occurs by chance. E-value (Expectation value): correction of the p-value for multiple testing.

In statistics, the symbol e is a mathematical constant approximately equal to 2.71828183.

The E-value can be calculated for an observed risk ratio (denoted RR) by E-value = R R + R R × ( R R - 1 ) . If the original risk ratio is below 1, then one first takes the inverse before applying the E-value formula.

The formula applies to a risk ratio greater than 1; for a risk ratio less than 1, one first takes the inverse of the observed risk ratio and then applies the formula. Thus for the risk ratio above of RR=3.9 one can obtain the E-value as follows: E-value=3.9+sqrt{3.9χ(3.9-1)}=7.2.

Importance of e

It is used to find derivatives and integrals in calculus. It is used in physics to calculate change and decay rates.

What is the e value symbol? ›

E is the symbol representing the base of the natural logarithm Log. It is also known as Euler's number and can be input as \[ExponentialE]. E has a number of equivalent definitions in mathematics, including as the infinite sum of reciprocal factorials over non-negative integers and as the limiting value .

The value of e is approximately 2.71828 (e is an irrational number, so any decimal representation of e will be approximate). Two common ways of calculating Euler's number are e = lim n → ∞ ( 1 + 1 n ) n and e = 1 + 1 1 ! + 1 2 !

The E-value is dependent on the length of the query sequence and the size of the database. For example, an alignment obtaining an E-value of 0.05 means that there is a 5 in 100 chance of occurring by chance alone. E-values are very dependent on the query sequence length and the database size.

An e-value of 0.0 means zero sequences can/are expected to match as well or better; the closer the e-value is to zero, the more significant (and less of a potential false positive) the match is considered to be.

However, they have limitations and are prone to misinterpretation. E-values have a monotonic, almost linear relationship with effect estimates and thus offer no additional information beyond what effect estimates can convey. Whereas effect estimates are based on real data, E-values may make unrealistic assumptions.

6e12 is shorthand for 6 x 10^12, which means 6 multiplied by 10 to the power of 12. To calculate the value of 6e12, first note that 10 to the power of 12 is equal to 1000000000000. Then, multiply 6 by 1000000000000 to get 6000000000000. Therefore, 6e12 is equal to 6000000000000.

To find the expected value, E(X), or mean μ of a discrete random variable X, simply multiply each value of the random variable by its probability and add the products. The formula is given as E ( X ) = μ = ∑ x P ( x ) .

Exponential Function

The value e is a constant (≈2.71828… ). We say a function is growing exponentially or has exponential growth when the rate at which it increases is proportional to its value: dydx∝y d y d x ∝ y .

If you get an E-value of 3 or less than you have a very good chance that the match is meaningful and not ue to random chance.