SOLUTION: What is the significance of a one-tailed test as opposed to a two-tailed test? What are the differences between accepting and not rejecting the null hypothesis?

Question 387945: What is the significance of a one-tailed test as opposed to a two-tailed test? What are the differences between accepting and not rejecting the null hypothesis?

Answer by robertb(5830) (Show Source): You can put this solution on YOUR website!
You use a one-tailed test when it seems that the statistic you got is either sufficiently greater OR lesser than what you believe to be is the parameter (or status-quo value). A two-tailed test is used when the statistic you got seems so close to the parameter you believe is true that the result could have gone either way, and so you never really know whether it is to the left or to the right of the (assumed ) parameter. "Accepting" and "not rejecting" the null hypothesis is just a matter of terminology: what is important is you stick to, or retain, the (assumed) parameter for the meantime.
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