Two-Tailed Test

A two-tailed test is a statistical procedure used to compare the null hypothesis (that a population parameter is equal to a particular value) against the alternative hypothesis (that the population parameter is different from this value). Evidence regarding the null hypothesis is obtained from a test statistic, and the test is said to be “two tailed” because its alternative hypothesis does not specify whether the parameter is greater than or less than the value specified by the null hypothesis. Hence, both large and small values of the test statistic, that is, values on both tails of its distribution, provide evidence against the null hypothesis. This type of test is relevant for situations in which researchers wish to test a null hypothesis, but they do not ...