Tests of statistical significance  one tailed and two tailed
When one think of tests of statistical significance, hypotheses must be considered first. With nondirectional null hypotheses, you are only suggesting that there will be a difference in mean score results. Which of the means will be higher is not speculated upon. In the case of a nondirectional null hypothesis, a twotailed test of significance is used.
If there is a prediction of which mean will be higher and which will be lower, then a onetailed test of significance is used. When you state a directional hypothesis, a onetailed test of significance is used.
Nondirectional null hypothesis = Twotailed test of significance
Directional null hypothesis = Onetailed test of significance
Return from tests of statistical significance to dissertation research questions and hypotheses.
