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Evidence · Intermediate · About 6 min

Interpret statistics

Lesson 6 of 10Step 1 of 5

Keep the unit and denominator attached

Both sides · Cross-examination
Read the fictional case: The four-day workweek
Both sides · Cross-examination

Resolution A four-day, 32-hour standard work week should replace the current five-day, 40-hour model

Fictional practice brief: ten volunteer office teams with 120 workers tried a 32-hour week for four weeks. Of 90 survey respondents, 72 preferred it. Weekly completed tasks rose from 100 to 104 across the same teams, while new software was also introduced. Customer coverage, pay, and long-term output were not measured.

A percentage is a share of a specific group. State who is in the denominator. Two percentages can both be correct while answering different questions.

Distinguish a count, a relative change and a percentage-point difference. The calculation can be simple; choosing the right measure determines what your argument actually claims.

Fictional practice record

72of 90 survey respondents
Preferred shorter hoursOther respondents

72 ÷ 90 = 80% of respondents preferred the shorter week.

72 ÷ 120 = 60% of all workers reported that preference. The 30 nonrespondents’ views are unknown.

  1. Name the unit

    Identify whether the figure concerns people, roles, tasks or a rate.

  2. Choose the denominator

    Keep the comparison group explicit.

  3. Describe the change

    Separate percentage points from a relative percentage change.

The same 72 workers, two different statements

Both sides · Cross-examination

Resolution A four-day, 32-hour standard work week should replace the current five-day, 40-hour model

Fictional practice brief: ten volunteer office teams with 120 workers tried a 32-hour week for four weeks. Of 90 survey respondents, 72 preferred it. Weekly completed tasks rose from 100 to 104 across the same teams, while new software was also introduced. Customer coverage, pay, and long-term output were not measured.

  1. Respondents
    72 of 90 respondents preferred the shorter week: 80%.

    This describes people who answered the survey.

  2. All workers
    72 of all 120 workers reported that preference: 60%.

    This does not tell us whether the 30 nonrespondents preferred it.

  3. Output change
    Tasks rising from 100 to 104 is a 4% relative increase.

    This is an output measure, not four percentage points in the preference survey.

A correct figure still needs the right claim attached to it.

Test the reasoning

Read the fictional practice case
Both sides · Cross-examination

Resolution A four-day, 32-hour standard work week should replace the current five-day, 40-hour model

Fictional practice brief: ten volunteer office teams with 120 workers tried a 32-hour week for four weeks. Of 90 survey respondents, 72 preferred it. Weekly completed tasks rose from 100 to 104 across the same teams, while new software was also introduced. Customer coverage, pay, and long-term output were not measured.

Quick check · 1 of 2Which statement preserves the survey calculation?

Your turn

Both sides · Constructive speech

Calculate each group’s shortlist rate and the percentage-point difference. Explain one claim this arithmetic cannot establish.

Read the fictional case: Meritocracy as practiced
Both sides · Constructive speech

Resolution Meritocracy as practiced in modern societies is a harmful fiction that should be rejected

Fictional practice brief: twenty of 100 applicants received interview coaching. Eight of those twenty and twelve of the other eighty were shortlisted. The record does not compare qualifications, explain who received coaching, or measure later job performance.

You can type or use your keyboard’s microphone to dictate. Your text stays editable. Practice is optional.

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Coached: … Uncoached: … Difference: … This does not establish…

Try it aloud

Use the timer for a spoken attempt if it helps. Practice without recording, then note what you would improve.

0:45

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Review and continue

Both sides · Constructive speech

Resolution Meritocracy as practiced in modern societies is a harmful fiction that should be rejected

Read the practice task and fictional case

Calculate each group’s shortlist rate and the percentage-point difference. Explain one claim this arithmetic cannot establish.

Fictional practice brief: twenty of 100 applicants received interview coaching. Eight of those twenty and twelve of the other eighty were shortlisted. The record does not compare qualifications, explain who received coaching, or measure later job performance.

Your response

You can return to the practice whenever you want.

One model response

Eight of 20 coached applicants is 40%; 12 of 80 uncoached applicants is 15%. The difference is 25 percentage points. The arithmetic establishes a rate difference in this fictional record, not that coaching caused it; qualifications and allocation were not compared.

The coached group contains 20 applicants.

Each rate uses its own group’s denominator. The answer distinguishes a measured difference from the explanation for it, leaving the observation available for a further argument.

Review the performance

  • EvidenceI use the correct denominator for each rate.
  • ClarityI distinguish percentage points from relative change.
  • ArgumentsI describe the claim the calculation actually supports.

Choose one move to improve, revise your response, then try it aloud.

Common mistakes to avoid
  • Dropping “of whom” when repeating a percentage.
  • Using correct arithmetic to imply an unsupported cause.

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Interpret statistics: SuperDebate Lesson | SuperDebate