The variance of $\bar { x } _ { 1 } - \bar { x } _ { 2 }$ is $V \left( \bar { x } _ { 1 } - \bar { x } _ { 2 } \right) = \frac { \sigma _ { 1 } ^ { 2 } } { n _ { 1 } } - \frac { \sigma _ { 2 } ^ { 2 } } { n _ { 2 } }$ .

Question

Quizplus · Accepted Answer

The variance of the difference between two sample means is the sum of their variances: $V \left( \bar { x } _ { 1 } - \bar { x } _ { 2 } \right) = \frac { \sigma _ { 1 } ^ { 2 } } { n _ { 1 } } + \frac { \sigma _ { 2 } ^ { 2 } } { n _ { 2 } }$.

The Variance Of xˉ1−xˉ2\bar { x } _ { 1 } - \bar { x } _ { 2 }xˉ1​−xˉ2​

The Variance Of $\bar { x } _ { 1 } - \bar { x } _ { 2 }$