Enter the sample size of the first sample, the sample size of the second sample, and the sample variance for sample 1 into the Pooled Variance Calculator. The calculator will evaluate the Pooled Variance. 

Pooled Variance Formula

The following formula is used to calculate the Pooled Variance. 

PV = (n-1)*S1 + (m-1)*S2 / (n+m-2)

Variables:

  • PV is the Pooled Variance ( )
  • n is the sample size of the first sample 
  • m is the sample size of the second sample 
  • S1 is the sample variance for sample 1 
  • S2 is the sample variance for sample 2

How to Calculate Pooled Variance?

The following steps outline how to calculate the Pooled Variance.

  1. First, determine the sample size of the first sample.
  2. Next, determine the sample size of the second sample. 
  3. Next, determine the sample variance for sample 1. 
  4. Next, determine the sample variance for sample 2.
  5. Next, gather the formula from above = PV = (n-1)*S1 + (m-1)*S2 / (n+m-2).
  6. Finally, calculate the Pooled Variance.
  7. After inserting the variables and calculating the result, check your answer with the calculator above. 

Example Problem:

Use the following variables as an example problem to test your knowledge.

sample size of the first sample = 34

sample size of the second sample = 100

sample variance for sample 1 = 13

sample variance for sample 2 = 13

PV = (n-1)*S1 + (m-1)*S2 / (n+m-2) =  ?