Back to Evaluate reports based on data — Problem 2 · Task Set 17

Exercises: Evaluate Reports Based on Data

Each report below makes a claim from data. Work through the four lenses: (1) the sample — who was studied and how were they chosen; (2) the design — does it license association only, or causation; (3) the uncertainty — is a sample size, margin of error, or significance disclosed; and (4) the display — is any graph honest. Write explanation answers in complete sentences. A causal verb ("causes," "raises") needs a randomized experiment; an observational study supports association only.

Grade 11·23 problems·~35 min·Common Core Math - HS Statistics and Probability·group·hss-ic-b-6

Work through problems with immediate feedback

Fluency: One Lens at a Time

Apply a single lens to each short report.

A website reports: "Our poll found 78% of people support the new policy." It does not say how many people were polled or how they were chosen. Applying the sampling lens, what is the best response?

The undisclosed sample size and selection method are themselves a red flag; the 78% cannot be judged as evidence about the population.

A 78% majority is large, so the sample must have been big and fair.

The result is fine as long as at least 30 people were polled.

Percentages from polls are always representative of everyone.