Shannon–Wiener diversity index

symbol: $H$
https://doi.org/10.1351/goldbook.15031
Index based on the assumption that all species are represented in the sample studied and that the sample was obtained randomly, giving the following mathematical relationship: \[H = -\sum \limits_{i=1}^S p_{i} \log p_{i}\] where \(p_{i}\) is the fraction of individuals belonging to the \(i\)-th species and \(S\) is the number of species.
Notes:
  1. The Shannon index is affected by both the number of species and their equitability, or evenness. Both a greater number of species and a more even distribution increase diversity as measured by \(H\).
  2. The most important source of error in this index is failure of sampling to include all species from the community of interest.
See also: diversity index
Source:
PAC, 2009, 81, 829. (Glossary of terms used in ecotoxicology (IUPAC Recommendations 2009)) on page 944 [Terms] [Paper]
Citation: 'Shannon–Wiener diversity index' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.15031 RIS BibTex EndNote
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