Tell an accurate story with data

Draft learning material, awaiting human review.

A bar chart is a clear starting point for comparing category totals. A line chart suits a time sequence. Label units, time period, and scope. Inspect truncated axes that can exaggerate small differences.

Compare rates when group sizes differ: 10 returns from 100 orders is 10%; 20 from 1000 is 2%. Averaging group averages without accounting for group sizes can give a misleading overall result.

Pivot-style summaries group records and aggregate values. When new rows arrive, check the source range and refresh requirements. Investigate missing months rather than silently treating them as zero. Conditional formatting highlights a rule; it does not prove the data is correct.

A group of 2 has mean 10 and a group of 8 has mean 20. The overall mean is (2*10+8*20)/10=18.