A reproducible chart starts before the chart

A chart's source link does not preserve the decisions that produced its values. This essay explains how a reproducible public graphic begins with a defined question, comparable quantities, and an explicit analysis record. NOAA's Arctic temperature chapter illustrates the importance of geographical coverage, water-year timing, baselines, and distinct input products. A simplified baseline example separates a changed reference from a changed observation, while noting that other processing choices can also differ. The proposed compact recipe retains input versions, retrieval dates, selections, weighting, filters, completeness rules, and transformation order. Climate and Forecast history conventions support this record but do not replace explanation. Accessible tables, labelled uncertainty, and distinctions between measurements and estimates help readers recover the calculation even when they disagree with its interpretation.