similarity coefficient

similarity coefficient

[‚sim·ə′lar·əd·ē ‚kō·i‚fish·ənt] (systematics) In numerical taxonomy, a factor S used to calculate the similarity between organisms, according to the formula S = ns /(ns + nd ), where ns represents the number of positive features shared by two strains, and nd represents the number of features positive for one strain and negative for the other.