# What is a pooled variance?

##### 1 Answer

#### Explanation:

Let consider we have two sets of data with

#((n_1-1)s_1^2+(n_2-1)s_2^2)/(n_1+n_2-2)#

You can combine more than two data sets also. If you have data sets with sizes

#((n_1-1)s_1^2+(n_2-1)s_2^2+...+(n_k-1)s_k^2)/(n_1+n_2+...+n_k-k)#

Also see the link for further information.

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