Enter the number of individuals of each species of up to 5 different species into the calculator to determine Simpson’s diversity index.

## Simpson’s Diversity Index Formula

The following formula is used to calculate Simpson’s Diversity Index.

D = 1 – [ sum(n*(n-1) / N*(N-1) ]

- Where D is the diversity index
- n is the number of individuals of each species
- N is the total number of individuals of all species

## Simpson’s Diversity Index Definition

**What is Simpson’s Diversity Index? **Simpson’s diversity index, or sometimes just referred to as the diversity index, is a measure that outlines how many different types there are in a dataset that can take into account the phylogentics relations amoung the individuals distributed amount those types. In otherwords, the biodiversity in different aspects of species.

## Example Problem

How to calculate Simpson’s Diversity Index?

**First, determine the number of individuals of each species.**For this example, there are 5 different species with counts of 10,20,15,12,8.

**Next, determine the total number of individuals of all species.**Adding together the numbers from step 1, we have a total of 65.

**Next, determine the sum of sum(n*(n-1)) of each individual species count.**For this example, that would be 10*(9)+20*(19)+15*(14)+12*(11)+8*(7) = 868.

**Next, determine the value of N*(N-1) where N is the total number of individuals of all species calculated in step 2.**N*(N-1) = 65*(65-1) = 4160.

**Finally, calculate the diversity index.**Using the formula above, we find the diversity index to be D = 1 – (868/4160) = .7913.

## About Simpson’s Diversity Index

**What is richness? **Richness quantifies the amount of different types the dataset contains.