Measures for presence/absence and ordinal data

The measures below are suitable for presence/absence (binary) data and ordered classes (e.g. "absent", "low abundance", "moderate abundance", "high abundance"). Note that ordered classes would be represented by dummy variables in order for these measures to be used. 

The coefficients suggested are usually similarity coefficients (S). Their one-complement (1-S) is their corresponding dissimilarity or, in the case of metric coefficients, distance coefficient. The "Sn notation was adopted by Legendre and Legendre (1998) and is reproduced below to assist cross-referencing.

References

• Legendre P, Legendre L. Numerical Ecology. 2nd ed. Amsterdam: Elsevier, 1998. ISBN 978-0444892508.

  • McCoy ED, Bell SS, Walters K (1986) Identifying biotic boundaries along environmental gradients. Ecology 67:749-759.

  • Raup DM, Crick RE (1979) Measurement of faunal similarity in paleontology. J Paleontol 53:1213-1227.