1. What is the Simpson Biodiversity Index?

The Simpson Biodiversity Index (λ) measures the concentration of dominance when individuals are classified into types (typically species). It represents the probability that two randomly selected individuals from a sample will belong to the same species.

2. How Does the Calculator Work?

The calculator uses the Simpson Index formula:

Where:

• \( \lambda \) — Simpson index (ranges from 0 to 1)
• \( p_i \) — Proportion of individuals belonging to species i
• \( S \) — Total number of species

Explanation: The index calculates the sum of squared proportions of each species in the sample. Higher values indicate lower diversity.

3. Interpretation of Results

Details:

• Simpson Index (λ): Ranges from 0 (infinite diversity) to 1 (no diversity)
• Simpson Diversity Index (1-λ): Ranges from 0 (no diversity) to 1 (infinite diversity)
• Simpson's Reciprocal Index (1/λ): Ranges from 1 (no diversity) up to the number of species (maximum diversity)

4. Using the Calculator

Tips: Enter counts of individuals for each species, separated by commas. For example, "5,10,3,2" means 5 individuals of species 1, 10 of species 2, etc.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between Simpson Index and Shannon Index?
A: Simpson Index gives more weight to dominant species, while Shannon Index is more sensitive to species richness.

Q2: When should I use Simpson Index?
A: Use when you want to emphasize dominant species in the community, particularly in conservation studies.

Q3: What does a Simpson Index of 0.5 mean?
A: There's a 50% chance that two randomly selected individuals will belong to the same species.

Q4: How does sample size affect the index?
A: The index is generally less sensitive to sample size than richness measures, but very small samples may underestimate diversity.

Q5: Can I compare indices from different studies?
A: Only if sampling methods were identical, as different collection methods can bias the results.