When Two Population Variances Are ____________________ We Estimate Each Population $\mu _ { 1 } - \mu _ { 2 }$

Short Answer

When two population variances are ____________________ we estimate each population variance with its sample variance. The test statistic of $\mu _ { 1 } - \mu _ { 2 }$ is approximately Student t-distributed with n₁ + n₂ - 2 degrees of freedom.