LEARN · EXPLAIN · REVISE

A questionnaire asks only classmates arriving before 8 am. Explain a coverage issue when estimating the whole school’s commute time.

Read the idea, work independently, then explain what changed.

TOPIC 01

Statistics: mixed assessment

A mixed assessment: identify the method, justify it and revise your reasoning.

Use one hint at a time. A correction explains what changed, not just the final answer.

01 / Foundation#Your turn

n=70

Skills and prerequisite lessons

Working and explanation

BUILD THE REASONING

Hint 1

State the survey question, population, sampling and measurement rules before drawing a conclusion.

Hint 2

Compare the sampling frame with the target population.

Worked solution

State the survey question, population, sampling and measurement rules before drawing a conclusion.
Calculate or simplify this relation.
$\text{sampling frame}\subsetneq\text{target population}$
More responses within the same restricted frame do not repair that exclusion.

Late-arriving students are excluded and may have systematically different commutes.

Checks and common pitfalls: More responses within the same restricted frame do not repair that exclusion.

Reasoning checklist · self / teacher assessment

Think first. Reveal a hint when the class is ready.

Teacher preparation and assessment