A Unit Label Is Small, but the Error Can Be Large

It is easy to infer a unit from a number, but temperature, flow, rainfall, and time can all be represented in different ways. When a label is missing, people supply the meaning they already expect, and correct data can lead to a wrong decision.

A rainfall value may represent an accumulated total over a period or a rate. A chart labeled only rainfall may not communicate that difference. When the time window changes, the interface should make clear how the number should be interpreted.

When converting units, verify the relationship between the source value and the displayed value. If several sources are placed side by side, converting them to the same unit does not erase differences in method.

I treat these small interface labels as part of the data. Removing units and time context may make a panel visually cleaner, but it also makes the statement incomplete. Precise display begins by preserving the identity of the number.

Source: official reference.