Simpson's Diversity Index Calculator
Measure biodiversity and species diversity in communities
Species Population Data
Input Requirements
- • Enter population counts for at least one species
- • Population values must be positive integers
- • All species with populations will be included in calculations
- • Species names are optional but helpful for identification
Step-by-Step Calculation Example
Example Community Data
Species A: 300 individuals
Species B: 335 individuals
Species C: 365 individuals
Total (N): 1000 individuals
Calculation Steps
Step 1: Calculate N(N-1) = 1000 × 999 = 999,000
Step 2: Calculate ni(ni-1) for each species:
• Species A: 300 × 299 = 89,700
• Species B: 335 × 334 = 111,890
• Species C: 365 × 364 = 132,860
Step 3: Sum = 89,700 + 111,890 + 132,860 = 334,450
Step 4: Simpson's Index D = 334,450 / 999,000 = 0.335
Step 5: Diversity Index = 1 - 0.335 = 0.665
Diversity Levels
0.0 - No Diversity
Single species dominance
0.0-0.4 - Low
Limited species diversity
0.4-0.6 - Moderate
Reasonable diversity
0.6-0.8 - High
Good species diversity
0.8-1.0 - Very High
Excellent diversity
Common Applications
Ecology: Measure biodiversity in ecosystems and habitats
Organizations: Assess diversity in workforce demographics
Research: Compare diversity across different populations
Conservation: Monitor ecosystem health over time
Understanding Simpson's Diversity Index
What is Simpson's Index?
Simpson's Diversity Index is a statistical measure that quantifies the diversity of species in a biological community. It reflects both the number of species present (richness) and the evenness of their distribution (abundance).
Index Variations
Simpson's Index (D): Probability that two randomly selected individuals belong to the same species
Diversity Index (1-D): Probability that two individuals belong to different species
Reciprocal Index (1/D): Effective number of species in the community
Key Properties
- ✓Range: Diversity Index ranges from 0 to 1
- ✓Higher values: Indicate greater diversity
- ✓Robust measure: Considers both richness and evenness
- ✓Widely applicable: Used beyond ecology
Formula Explanation
ni: Number of individuals in species i
N: Total number of individuals
Σ: Sum across all species
Practical Examples
Forest Ecosystem
A forest with many tree species in equal proportions would have a high diversity index (approaching 1), indicating excellent biodiversity.
Corporate Diversity
Organizations use Simpson's index to measure workforce diversity across ethnicities, genders, or departments for inclusion metrics.
Market Analysis
Economists apply the index to measure market concentration and competitive diversity among companies in different sectors.
Interpretation Guidelines
High Diversity (0.7-1.0)
- • Many species with similar populations
- • Low probability of selecting same species twice
- • Indicates healthy, stable ecosystem
- • Greater resilience to environmental changes
Low Diversity (0.0-0.3)
- • Few species or one dominant species
- • High probability of selecting same species twice
- • May indicate ecosystem stress
- • Less resilient to disturbances