One-tailed refers to a type of hypothesis test where the alternative hypothesis specifies a direction of the effect or difference being tested. In a one-tailed test, researchers look for evidence that the parameter of interest is either greater than or less than a specified value, but not both; for example, a one-tailed test might assess whether a new drug leads to an increase in recovery rates compared to a placebo, focusing only on the possibility of improvement rather than any change in either direction.

 A one-tailed test results from an alternative hypothesis which specifies a direction.

One-tailed refers to a statistical test where the hypothesis is tested in one direction.

One-tailed means that the hypothesis test is focused on detecting an effect in a specific direction, either greater than or less than a certain value, allowing for the rejection of the null hypothesis only if the test statistic falls in one tail of the distribution.

results from an alternative hypothesis which specifies a direction