**Simpson’s Diversity Index** is a way to measure the diversity of species in a community.

Denoted as *D*, this index is calculated as:

*D* = Σn_{i}(n_{i}-1) / N(N-1)

where:

**n**The number of organisms that belong to species_{i}:*i***N:**The total number of organisms

The value for Simpson’s Diversity Index ranges between 0 and 1. The higher the value, the lower the diversity.

Since this interpretation is a bit counterintuitive, we often calculate **Simpson’s Index of Diversity** (sometimes called a Dominance Index), which is calculated as 1 – D. The higher the value for this index, the higher the diversity of species.

We can also calculate **Simpson’s Reciprocal Index**, which is calculated as 1/D. The lowest value for this index is 1 and the highest value is equal to the number of species.

For example, if there are 7 different species then the max value for this index would be 7. The higher the value for this index, the greater the diversity of the species.

The following step-by-step example shows how to calculate these various indices for a given community.

**Step 1: Collect the Data**

Suppose a biologist wants to measure the diversity of species in a local forest. She collects the following data:

**Step 2: Calculate N**

Next, she can calculate the total number of organisms.

There are **105** total organims.

**Step 3: Calculate n**_{i}(n_{i}-1)

_{i}(n

_{i}-1)

Next, she can calculate n_{i}(n_{i}-1). For example, the first species would be calculated as 40*(40-1) = 1,560. She can repeat this calculation for each species:

**Step 4: Calculate Simpson’s Diversity Index**

Lastly, we can use the following formula to calculate Simpson’s Index:

*D* = Σn_{i}(n_{i}-1) / N(N-1)

Using the values we found earlier, **Simpson’s Index** can be calculated as:

*D* = 2,668 / (105*(105-1)) = **0.244**.

We can also calculate **Simpson’s Index of Diversity** as 1 – *D* = 1 – 0.244 = **0.756**.

We can also calculate **Simpson’s Reciprocal Index** as 1 / *D* = 1 / .244 = **4.09**.

**Additional Resources**

Feel free to use this Simpson’s Diversity Index Calculator to automatically calculate Simpson’s Diversity Index for any dataset.

Got to learn many things

Thanks for sharing. Hope these information will be useful

But little confused in my case