The Extreme Value Distribution (EVD) models the probability distribution of random variables representing the maximum value within a set of samples, distinguishing itself from standard Gaussian distributions by utilizing parameters $\lambda$ and $k$. This theoretical framework is applied in bioinformatics to evaluate the statistical significance of alignment scores generated by algorithms like BLAST, specifically determining whether high-scoring segment pairs (HSPs) occur by chance or reflect biological homology. By characterizing the tail behavior of random search spaces rather than assuming normality for all data points, EVD provides the rigorous mathematical basis for calculating Expectation values ($E$) and Bit scores to filter biologically meaningful sequence matches from random noise.
The Extreme Value Distribution (EVD) models the probability distribution of random variables representing the maximum value within a set of samples, distinguishing itself from standard Gaussian distr…