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.
Fluency: One Lens at a Time
Apply a single lens to each short report.
A report passes the sampling lens (large random sample) and the design lens (randomized experiment with a significance check), but its only chart uses a y-axis starting at 95 to make a 1-point difference look enormous. Write a one-sentence calibrated verdict that names the strength AND the weakness, rather than declaring the whole report worthless.