similarity coefficient Any measure of the similarity of two samples. In ecological work the similarity index devised in 1920 by H. A.Gleason has been widely used. This measures similarity as C = 2W/(a + b), where a and b are the quantities of all the species (or other commodity) found in the two units to be compared, and W is the sum of the lesser values for those species common to both units. Complete similarity thus scores 1, complete dissimilarity 0. See also affinity index.

similarity coefficient Any measure of the similarity of two samples. In ecological work, the similarity index devised in 1920 by H. A. Gleason has been widely used. This measures similarity as C = 2W/(a + b), where a and b are the quantities of all the plants (or another commodity) found in the 2 stands, or other units to be compared, and W is the sum of the lesser values for those species common to both units. Complete similarity thus scores 1, complete dissimilarity 0. See also AFFINITY INDEX.

similarity coefficient Any measure of the similarity of two samples. In ecological work, the similarity index devised in 1920 by H. A. Gleason has been widely used. This measures similarity as C = 2W/(a + b), where a and b are the quantities of all the species (or other commodity) found in the two units to be compared, and W is the sum of the lesser values for those species common to both units. Complete similarity thus scores 1, complete dissimilarity 0. See also AFFINITY INDEX.