S2.4.4 - Critical region

Critical region.; Use of a statistic as a test statistic.

Use critical region to connect the rule to the data and decision in the question.

This matters because critical region determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply critical region to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: Critical region is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.