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Identify who and what the numbers describe

About 25 minutes · 7 reading + 18 practice and checks
Time includes reading, practice, and questions. Extra videos or further study are optional.
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Audit the supplied fictional claim about a reminder app using sampling, summary, conditional-rate, uncertainty, and causal-reasoning tools.

Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.

What to include

  • Identify the claim, population, sample, unit of observation, and sampling limits.
  • Calculate and compare mean, median, absolute change, and relative change where appropriate.
  • Use a natural-frequency table to compute a conditional percentage with the correct denominator.
  • Interpret a supplied confidence interval without treating it as individual variation or certainty.
  • Write a claim verdict that separates supported description from unsupported causation and names needed evidence.

Review and revise

Use these criteria to check your work and choose what to improve.

  • Calculation: quantities and denominators are correct and reproducible.
  • Scope: sample and population claims are distinguished.
  • Uncertainty: intervals and study limits are explained accurately.
  • Judgment: the conclusion is proportional to the evidence and identifies a useful next question.
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Before you begin

The idea in everyday life

Statistics often arrive as a polished headline with the selection process hidden. Before debating the result, identify who or what was actually counted and how those observations entered the dataset. A large or precise-looking number does not automatically represent the intended population. This lesson builds the claim map that will guide your final audit.

The idea

Always ask who was counted. A percentage about the people surveyed does not automatically describe everyone.

Try it

One step at a time.

Use the sample or information you have permission to use. Keep your work as you go. You can pause between steps.

  1. 1

    Copy the fictional headline and identify its population claim. Then list the actual sample, sample size, question asked, and how respondents were selected.

  2. 2

    Calculate 18 divided by 20 as a percentage. Keep the arithmetic judgment separate from whether the sample represents all learners in the headline.

  3. 3

    Name at least two groups whose views may be missed by the selection method, such as learners unavailable in the evening or those not choosing the workshop.

  4. 4

    Rewrite the headline as “18 of 20 evening-workshop respondents want more evening sessions.” Add a sentence identifying both the unresolved all-learner claim and the unasked comparison with other instructional times.

  5. 5

    Propose a better way to seek the wider population’s views, including a method that reaches absent learners. Save the claim map, corrected wording, and sampling question for the audit brief.

Example

See how it works.

Fictional scenario: A training center asks people leaving an optional evening workshop whether they want more evening sessions. Eighteen of twenty respondents say yes, producing 90%. A headline says “90% of all learners prefer evening instruction.” Ren identifies the population as all center learners, the sample as twenty workshop respondents, and the selection process as a convenience opportunity among people already able to attend evenings. The 90% describes respondents wanting more sessions; it neither establishes preference over other times nor represents all learners. Ren also distinguishes a request for more sessions from evidence that evening sessions improve learning.

Check your work

Did you cover these?

  • The respondent percentage is 90%.
  • The sample is identified as evening-workshop respondents.
  • The revised headline describes wanting more evening sessions among respondents; it does not claim all-learner preference.
Your work

What to finish

A claim-and-sample map, recomputed percentage, and a scope-corrected headline.

Common mistake

Watch for this

Assuming correct arithmetic makes a sample representative or proves an outcome the survey never measured.

How can I tell I understand it?

You distinguish the counted group from the claimed population and explain a selection concern.

Try 3 questions

Quick knowledge check

Answer all 3 questions. Get at least 2 right and the lesson completes automatically.

Not yet passed

You’ll get an explanation for each answer. Signed in? Your results save to your account.

1A poll on a cycling club website gets 80 of 100 responses favoring more bike racks. What is directly supported?
2A sample includes only daytime visitors, but the claim concerns all visitors. Which improvement addresses coverage?
3A service logs 500 visits. Which additional claim requires a different kind of record?
0 of 3 answeredApply the lesson to a short question, then review the explanation.
1
Finish this lesson

Pass the check. We’ll save the progress.

Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.

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Sources and further reading

Explore the references behind this lesson.

OpenStax, Introductory Statistics 2e: Data, Sampling, and Variation
Source & access notes · checked 2026-09-10

Opened sampling methods, data types, and variation discussion. Supports identifying sample design and scope; no book examples are reused.

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