Pooled Two Sample T Test Formula. The formula to calculate a pooled standard deviation for two groups is as follows. This does not calculate the confidence interval which i m calculating by.
This is equal to the denominator of t in theorem 1 if b true default and equal to the denominator of t in theorem 1 of two sample t test with unequal variances if b false. T x 1 x 2 μ 1 μ 2 s p 2 1 n 1 1 n 2 t frac overline x 1 overline x 2 mu 1 mu 2 sqrt s p 2 frac 1 n 1 frac 1 n 2 t s p 2 n 1 1 n 2 1 x 1 x 2 μ 1 μ 2. The formula for the pooled estimator of σ 2 is.
For this reason the pooled variance method should be used with caution.
T x 1 x 2 μ 1 μ 2 s p 2 1 n 1 1 n 2 t frac overline x 1 overline x 2 mu 1 mu 2 sqrt s p 2 frac 1 n 1 frac 1 n 2 t s p 2 n 1 1 n 2 1 x 1 x 2 μ 1 μ 2. Where s 1 and s 2 are the standard deviations of the two samples and n 1 and n 2 are the sizes of the two samples. This does not calculate the confidence interval which i m calculating by. Pooled variance t procedure in ms excel.
