Pooled Standard Deviation Calculator
Calculate pooled standard deviation from two independent groups. Used in t-tests with equal variance assumption.
Enter Group Data
Example Data Sets:
Pooled Standard Deviation
2.517041
Pooled Variance
6.335498
Degrees of Freedom
11
Group 1:
n1:
6
Mean:
28.8333
Std Dev:
2.639444
Group 2:
n2:
7
Mean:
38.8571
Std Dev:
2.410295
Combined Sample Size
13
What is Pooled Standard Deviation?
Pooled standard deviation combines the variability from two or more groups into a single estimate, assuming all groups have equal population variances. It is the square root of the pooled variance and is commonly used in two-sample t-tests and ANOVA.
Formula
Sp = sqrt[(SS1 + SS2) / (n1 + n2 - 2)]
Where SS1 and SS2 are the sum of squared deviations from each group.