In this article, we will demonstrate how to calculate **Pooled Variance** in Excel.

**What Is Pooled Variance?**

Pooled Variance is a statistical term also known as combined variance or composite variance. It indicates the average variance of two or more groups, and represents the single common variance among the groups.

Mathematically, **Pooled Variance** can be expressed as:

Where,

**n _{1 }**= Sample size of

**Group 1**,

**n _{2 }**= Sample size of

**Group 2**,

**S _{1}**

**= Variance of**

^{2 }**Group 1**,

**S _{2}^{2 }**= Variance of

**Group 2**, and

**S _{p}^{2}** = Pooled Variance.

When the sample sizes are the same (**n _{1}=n_{2}**), we can use the following simplified formula:

**How to Calculate Pooled Variance in Excel**

**Step 1 – Input Data and Form a Table**

First, we collect sample data to make a dataset and form a **Table**, which** **will simplify our calculation.

- Insert sample data from two different sources into the columns
**Group 1**and**Group 2**.

Now we form two tables from this data.

- Select the cells of the
**Group 1**column. - Select
**Table**from the**Insert**tab.

The **Create Table** window appears. Our selected range is pre-selected.

- Check
**My table has headers**option. - Click
**OK**.

Click on the **Table Design **tab.

- Uncheck
**Filter Button**and**Banded Rows**from the**Table Style Options**section. - Set the name of the table in the
**Table Name**field.

- Similarly, create the other table named
**Group2**.

In the dataset, the little arrow in the bottom-right corner of the table denotes that it’s a Table.

**Read More: **How to Do Variance Analysis in Excel

**Step 2 – Count the Number of Samples**

**The COUNT function** counts the number of cells in a range that contains numbers.

Using the 2 tables just created, we’ll now determine the size of the sample data using the **COUNT **function.

- Add a row to store the sample sizes.

- In cell
**C16**, enter the following formula:

`=COUNT(Group1)`

- Press
**Enter**.

The data size of **Group1** is returned.

- Insert a similar formula for the
**Group2**table.

**Read More: **How to Apply Variance Formula in Excel to Get Plus-Minus Results

**Step 3 – Calculate the Variance with the VAR.S Function**

The** VAR.S **function estimates variance based on a sample (ignoring logical values and text in the sample).

With the sample sizes determined, we can determine the variance using Excel’s default variance function.

- Add a new row to store the variance figures.

- In cell
**C17**, enter the following formula:

`=VAR.S(Group1)`

- Press
**Enter**to return the result.

The variance for the data of the **Group 1** column is returned.

- Create a similar formula for
**Group 2**in cell**D17**and press**Enter**.

As we are using a **Table **as a reference, the **Fill Handle** will not work here.

**Read More: **How to Calculate Sample Variance in Excel

**Step 4 – Determine Pooled Variance with a Formula**

With the variances determined, we can calculate the **Pooled Variance **by applying a mathematical formula.

- Add a row for the
**Pooled Variance**figures.

- Enter the following formula in cell
**C18**:

`=((C16-1)*C17+(D16-1)*D17)/(C16+D16-2)`

- Press
**Enter**to return the result.

As discussed above, when the sample sizes are the same, we can use a simplified formula.

- Insert the following simplified formula in cell
**C19**:

`=(C17+D17)/2`

- Press
**Enter**to return the result.

**Read More:** How to Calculate Percentage Variance between Two Numbers in Excel

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## Related Articles

- How to Calculate Coefficient of Variance in Excel
- How to Calculate Mean Variance and Standard Deviation in Excel
- How to Find Population Variance in Excel
- How to Find the Variance of a Probability Distribution in Excel

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