Confidence Intervals for μ 1 − μ 2: Pooled Variances. When we have good reason to believe that the variance for population 1 is equal to that of population 2, we can estimate the common variance by pooling information from samples from

Solve Now
Here is how to calculate the pooled variance between the two samples: sp2 = ( (n1-1)s12 + (n2-1)s22 ) / (n1+n2-2) sp2 = ( (40-1)*18.5 + (38-1)*6.7 ) / (40+38-2) sp2 = (39*18.5 +

Variance = σ 2 = ∑ i = 1 n ( x i − μ) 2 n For a Sample Population divide by the sample size minus 1, n - 1 Variance = s 2 = ∑ i = 1 n ( x i − x ¯) 2 n − 1 The population standard deviation is the square root of the population variance.

Get Started