QS4—Index numbers

Interpret index numbers.

Use qs4—index numbers to connect the rule to the data and decision in the question.

This matters because qs4—index numbers determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply qs4—index numbers to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: QS4—Index numbers is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.