Before reusing a chart's numbers, separate what the source labels from what you infer. A longer bar, a familiar colour or a precise-looking decimal is not enough to support a numerical statement.
This manual exercise uses three fictional text cards and deliberately unsupported practice conclusions. They were written for teaching: there is no chart image, PDF, OCR output, AI response or product test behind them. It teaches checking logic, not actual figure transcription.
Start with one claim
For a real document, use material you may inspect and keep the original unchanged. Record the file and revision, viewer page, printed page label if different, and figure or panel.
Include the caption and relevant conditions in your reviewed scope. This identifies what your check covers before you judge the claim.
Write the claim you intend to reuse. Then identify the evidence needed: numerical labels, a series identity, or a point's position. W3C's complex-image guidance distinguishes chart structure from its values and describes including scales and relationships in a full description. This guidance supports separating appearance from data, not AI accuracy.
Try the three cards
Read the practice cards before the answer table. For Card A, calculate from the stated values, not the amount of bar extending above the baseline. Keep the value ratio, absolute increase and percentage increase separate. The ratio of bar lengths answers a different question from the ratio of values.
For Card B, locate the evidence naming the series. Colour identifies a visual element here, not a team. If the legend is missing, do not import an identity from a similar-looking chart elsewhere.
For Card C, ask what supports the decimal places. Being between two ticks does not establish a precise value. This card supplies no defensible point estimate; keep the exact value unknown. In a real figure, report an estimate only when its detail and scale support one, label it estimated, and state the basis.
Fictional practice cards
These text descriptions and deliberately unsupported practice claims are authored teaching material, not a real chart, customer file, model answer or test result. Locators are invented. Scope: only Cards A–C below.
Fictional Cedar chart practice, revision 1
Card A / practice page 1 / Figure A
Topic: boxes shipped on Monday and Tuesday.
Y-axis minimum: 10 boxes; ticks: 10, 20, 30.
Explicit value labels: Monday 20 boxes; Tuesday 30 boxes.
Described lengths above the baseline: 10 and 20 scale units.
Deliberately unsupported practice claim: Tuesday doubled Monday.
Card B / practice page 1 / Figure B
A blue series is visible; its legend label is missing.
Deliberately unsupported practice claim: The blue series is Team A.
Card C / practice page 2 / Figure C
A point lies between ticks 10 and 20.
No exact point label or data table is supplied.
Detail is insufficient for a precise reading or defensible point estimate.
Deliberately unsupported practice claim: The value is 12.47.Expected answers—not performed tests
| Card | Evidence status | Expected correction or stop |
|---|---|---|
A | Source-reported exact labels: 20 and 30 boxes, at their stated precision. | Derived ratio: 30 / 20 = 1.5. Absolute increase: 30 - 20 = 10 boxes. Relative increase: (30 - 20) / 20 = 0.5 = 50%. Above-baseline length ratio: (30 - 10) / (20 - 10) = 2; that is not the value ratio. Reject “doubled.” |
B | Team identity: unknown. | The missing legend does not establish Team A. Ask for a labelled source; do not infer identity from colour alone. |
C | Exact value and usable point estimate: unknown. | Do not reuse 12.47 as a source-supported exact value. Only “between 10 and 20” is supplied. Request a clearer source or underlying values; do not invent an estimate. |
Record what is known
Use the small record below. Classify a directly labelled number as source-reported exact at the displayed precision. Mark approximate readings estimated; leave unsupported identities or precise values unknown. Record calculations separately, with their inputs and formula; they are not labels transcribed from the chart.
Copyable review record
Source filename / revision:
Viewer page / printed page label / figure or panel:
Claim to check:
Evidence location, wording, unit and relevant conditions:
Classification: source-reported exact / estimated / unknown
Displayed precision or estimate basis:
Derived calculation, inputs and formula (if any):
Correction or stopping action:
Reviewed scope and unresolved questions:
Reviewer / date:
Recheck if source, scope or claim changes.An exact label is exact only as reported, not a guarantee about the measurement or the world. This worksheet does not validate other figures or demonstrate any product's parsing capability.
If the original is blurred or ambiguous, stop and request a clearer authorized source or its supporting data. The scanned-text checking guide covers checking readable text against its source; neither that check nor enlargement guarantees recovery of missing detail.
Before sharing, retain unresolved questions alongside the claim. Review only the identified figures and conditions; checking one number does not certify the whole document. Source support does not establish real-world truth. Recheck whenever the file, figure or question changes.