Final Answer:
If the alternative hypothesis includes the symbol <, the rejection region is in the upper tail is True.
Step-by-step explanation:
The statement is true. The placement of the rejection region in hypothesis testing depends on the direction of the alternative hypothesis. If the alternative hypothesis includes the symbol < (less than), it implies that we are interested in detecting a decrease or reduction in a parameter. In this case, the rejection region is in the upper tail of the distribution.
When testing a hypothesis, we set up a null hypothesis
and an alternative hypothesis
. The null hypothesis typically includes a statement of no effect or no difference, while the alternative hypothesis indicates the direction and nature of the effect we are trying to detect. If the alternative hypothesis suggests a less-than relationship, the rejection region is in the upper tail because we are looking for evidence of a decrease or reduction.
For example, in a one-tailed test where the alternative hypothesis is
(indicating a decrease in the population mean), the rejection region will be in the upper tail of the distribution. This region is chosen based on the chosen level of significance
and critical values. The rejection region in the upper tail signifies the extreme values of the test statistic that would lead to rejecting the null hypothesis in favor of the alternative hypothesis.