Which Simpson value should I report?

Report the form your class, paper, or protocol expects: D, 1-D, or 1/D.

Can counts be percentages?

Use raw counts when possible. Percentages can work if all values share the same scale and totals are meaningful.

Enter species abundance counts and calculate Simpson diversity, dominance, reciprocal index, and species contributions.

Answer

0.6939

Simpson diversity 1-D

Simpson dominance D: 0.3061

Reciprocal index 1/D: 3.2673

Species richness: 4

Total individuals: 100

SpeciesCount

Examples

Dominant species

Species A · 42%

Species contributions

Species	Count	Proportion	Contribution to D
Species A	42	42%	0.1739
Species B	31	31%	0.0939
Species C	18	18%	0.0309
Species D	9	9%	0.0073

D = sum(n_i(n_i - 1)) / (N(N - 1)); diversity = 1 - D

D is dominance. A lower D and higher 1-D usually indicate greater diversity.

Use the same Simpson form consistently when comparing sites.

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