Unit 01.04: The one sentence a chart has to earn

Every chart should earn one sentence, and the sentence should be written first.

A claim, not a description

A takeaway sentence makes a claim the chart can support or fail to support. A description says what the axes are.

The code sorts four candidate sentences.

SENTENCES = [
    ("Revenue grew 18% over the year, driven entirely by the North region.",
     True,  "specific, and the chart can show both claims"),
    ("Revenue performance was strong.",
     False, "no figure, no comparison, nothing to check"),
    ("Defect rate exceeded target in weeks 14 and 15.",
     True,  "names the exception and where to look"),
    ("This chart shows revenue by region over time.",
     False, "describes the chart, does not say anything"),
]
print(f"{'candidate takeaway sentence':64} earns the chart?")
for sentence, ok, why in SENTENCES:
    print(f"{sentence:64} {'yes' if ok else 'NO':4} {why}")

# Write the sentence first, then build the chart that supports it. A chart
# whose sentence is "this chart shows X" has no finding in it, and the reader
# has to do the analysis you were supposed to have done.

"This chart shows revenue by region over time" describes the chart and asserts nothing - the reader still has to do the analysis. "Revenue grew 18%, driven entirely by the North region" makes two claims, and the chart either supports both or it needs redesigning.

Writing it first also stops you building charts that support no clause of anything, which is the main source of dashboard sprawl.

The mistake this prevents

The mistake is writing the title after the chart, from what the chart happens to show. The title is the finding; the chart is the evidence. Reversing that order produces charts in search of a conclusion.

Takeaway

Write the takeaway sentence before building the chart, as a claim with a figure in it. The chart's job is to support it.

Mark complete