They are used to test hypothesis such as the mean is some value where you do not know if otherwise the mean is less or more.
Chat with our AI personalities
The choice of one-tailed or two-tailed tests follows the logic of the hypothesis that is being tested! The one-tailed test, if appropriate, will be more powerful.
no tail
· One-tailed test looks at the probability that the sample mean was either "greater than", or "less than or equal to" · Two-tailed test, sees if two means are different from each other (ie from different populations), or from the same population and tries to establish "equal to" or "not equal to
You could use a two-tailed t-test. You would use a two-tailed test instead of a one-tailed test because you are not hypothesizing which direction the difference will be. If you hypothesize before hand the direction of change, you could use a one-tailed test.
-2.58,2.58