Choosing the Right Chart

Every chart answers one kind of question well and others badly. Choosing is a translation task:

• Comparison — which region sells most? → bar chart. Length is what eyes compare most accurately.
• Trend — is churn rising? → line chart. Position along a time axis shows direction at a glance.
• Distribution — how spread out are order sizes? → histogram or box plot.
• Relationship — does ad spend track revenue? → scatter plot.
• Composition — what share comes from each channel? → stacked bar; a pie, reluctantly.

Start from the question, not the data. 'Trend over time' drawn as bars is the classic mistake — technically valid, cognitively wrong.