Rule of Uncertainty
Missing and estimated values remain distinguishable.
Requirement
Missing, unavailable, and suppressed values must remain distinct from observed zero. Forecasts, estimates, and measured values must be visibly distinguishable. Disclose interpolation across missing observations and material omissions or truncation. Show supplied uncertainty when it affects interpretation.
Why
A continuous line or an apparently complete table must not imply evidence that does not exist.
Application
A gap or labeled missing value is valid. Connecting observations across a gap requires an explicit indication that intervening values are missing. Do not invent an uncertainty interval when the underlying data provides none.
Examples
The pair isolates this rule. A good example is not approval of the entire interface.
Good for this task
Unavailable, estimated, and observed-zero values use distinct labels and marks.
Daily parcel observations
Monday: 0 parcels (observed)
Bad for this task
Missing values are rendered as zero and forecasts look identical to observations.
Daily parcel observations
Monday: 0 parcels (observed)
These synthetic fixtures illustrate the stated comparison. Native checks can support review of declared scales, context, encodings, geometry, and legibility; they do not establish data truth or task relevance. Review the requirement and exceptions above.
Enforcement
automated is the strongest mechanism Viewrule expects for the complete rule. Partial checks can still provide supporting evidence without proving the whole requirement.