– A one-tailed test is a test of a statistical hypothesis designed to show that the sample mean will be above or below the population mean, but not both.#
When using a one-way test, the analyst tests the possibility of a connection in one direction of interest and completely ignores the possibility of a connection in the other direction.
Before running a one-tailed test, the analyst must establish the null and alternative hypotheses and set the probability value (p-value).