Enter the number of elements in common, the number of elements in set 1, and the number in set 2 into the calculator to determine the Sorensen index.

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## Sorensen Index Formula

The following equation is used to calculate the Sorensen Index.

SI = (2*EC) / (E1 + E2)

- Where SI is the Sorensen Index
- EC is the total number of elements in common between the sets
- E1 is the number of elements in set 1
- E2 is the number of elements in set 2

To calculate the Sorensen Index, multiply the number of elements in common by 2, then divide by the sum of the number of elements in each set.

## What is a Sorensen Index?

Definition:

The Sorensen Index, also known as the **Sorensen-Dice Coefficient**, is a statistic used to measure the similarity of two samples of data.

## How to Calculate Sorensen Index?

Example Problem:

The following example outlines the steps and information needed to calculate Sorensen Index.

First, determine the number of elements in common. For this example, the number of elements in common is 50.

Next, determine the number of elements in set 1. In this case, the elements in set 1 are counted as 150.

Next, determine the number of elements in set 2. This is measured to be 200.

Finally, calculate the Sorensen Index using the formula above:

SI = (2*EC) / (E1 + E2)

SI = (2*50) / (150 + 200)

SI = .285