Question

When would you use a one-tailed rather than a two-tailed t-test when checking significance levels?

Answer 1

Here we would use a one- tailed test rather than a two tailed t - test when checking signiciance level when it is desired to check if one sample mean is greater or lesser than the other mean. That mean when the test has a direction, either positive or negative. 2 - tailed test tells us that one mean is different from the other mean or belong to different - different population but it doesn't tell us which mean is larger or smaller. One tailed t - test is used for that purpose.