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A one-tailed test allocates the entire significance level $\alpha$ to its designated tail. Unlike a two-tailed test which splits $\alpha$ into $\alpha/2$ for each tail, a one-tailed test places all of $\alpha$ in either the left or the right tail, depending on the direction specified by the alternative hypothesis.

Conditions: The test is one-tailed.; The significance level is $\alpha$.; The direction is specified by the alternative hypothesis ($<$ or $>$).

A one-tailed test allocates the entire significance level $\alpha$ to its designated tail. Unlike a two-tailed test which splits $\alpha$ into $\alpha/2$ for each tail, a one-tailed test places all of $\alpha$ in either the left or the right tail, depending on the direction specified by the alternative hypothesis.

Conditions: The test is one-tailed.; The significance level is $\alpha$.; The direction is specified by the alternative hypothesis ($<$ or $>$).

In a symmetric two-tailed construction, the significance level $\alpha$ is split equally between the two tails. Each tail receives $\alpha/2$.

Conditions: The test is a symmetric two-tailed test.; The significance level is $\alpha$.

In a symmetric two-tailed construction, the significance level $\alpha$ is split equally between the two tails. Each tail receives $\alpha/2$.

Conditions: The test is a symmetric two-tailed test.; The significance level is $\alpha$.