# Missing data

Metadata is often missing—but data istelf is often missing, too!
Even within a given data set, a value like 0 might actually mean zero—or it might simply mean that the data was not recorded.
Some data isn't just missing within a dataset; it's missing altogether!
Missing data is a concept that describes phenomena that have not been recorded into datasets; we may not even realize that these phenomena exist! For one reason or another (or many reasons), these phenomena are rarely or never documented.
The lack of data about the phenomena does not mean they don't occur
- Centuries of societal norms and thought practice have built up into what is recorded and mapped and what is not.
Sometimes there are strategic explanations for missing data such as concerns for the privacy and safety of those involved in a situation.
We hope this course empowers you to identify what isn't being mapped, identify why, and then figure out what you can do about it!