Missing is not a number — Cobalt & Frontier

A blank cell may mean a question was not answered, a measurement was unavailable, or the field did not apply. Treating all of those cases as zero can change the meaning of a calculation.

Decide how missing values are represented and explain the choice. Check whether a summary excludes them or replaces them with another value. The reason information is missing can matter as much as the amount missing.

Look at a few absent values in their original context before choosing a rule. Preserve distinctions that affect the question, and avoid filling gaps merely to make the table look complete. Honest incompleteness can be more informative than a tidy but misleading number.

A few starting points

Ask why the value is absent.
Document how calculations handle missing values.
Avoid silently replacing every blank with zero.

Try the idea in context.

Consider a temperature record with a gap during an unavailable reading. Substituting zero would describe a physical observation that never happened.

A thought for the next read.

Treat an unexpected value as the start of an investigation. Its source and context matter before you decide whether to remove it or build a story around it.