Briefle words · Data & charts
Reference line
Also called target line
A line drawn across a chart at a meaningful fixed value, such as a target, average or limit, so readers can judge the data against it at a glance.
Say it to an AI
Line chart of weekly on-time delivery for eight weeks on a 90 to 100% axis. Add a reference line (target line) at 95%, dashed and red with an annotation 'Target 95%' at its right end, so weeks below target are obvious; keep the target in the subtitle too.
How an expert would brief the stronger version of “On-time delivery chart”.
See it
Try it as a puzzle →Weekly service-level chart on the operations dashboard of a meal-kit delivery company.
Why: B's dashed red line at 95% with its 'Target 95%' label; A has only the regular 90, 95 and 100 gridlines.
More ways experts use it
Horizontal bar chart of 5xx rate per service with a dashed reference line (target line) at the 1% SLO. Flag breaches with redundant encoding: red fill plus a '▲ over SLO' text tag beside the value, so the status never depends on color as the only visual means.
Error rate by service · Data & charts
Related words
Room 4 · Labels & annotations
Learn “Reference line” in a five-minute lesson