Position for quantities

Claim: a figure that shows a quantity shows it by position on a common scale, or by length, before angle or area.

• Grade: measured, for charts.
• Evidence: review, strand 2.
• Check: figure-judgment (judgment): is a quantity shown by area or angle where position would do?
• Reader styles: none changes it.

What it asks

• Prefer a dot or a bar on a common axis to a pie, a bubble or a 3D mark.
• Align bars on one baseline, side by side.

Why

Readers judge position on a common scale most accurately (Cleveland 1984). A crowdsourced replication kept the ranking: position beat length, and area did worse than angle (Heer 2010). Aligned and adjacent bars beat stacked and separated ones (Talbot 2014).

Limits

• Angle was not worse than length in the replication (Heer 2010).
• The evidence is for charts; a diagram's boxes and links carry no quantity.